Document:

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                                                                     Exhibit 4.5

                        AMERICAN TOWER ESCROW CORPORATION

                                     ISSUER

               12.25% SENIOR SUBORDINATED DISCOUNT NOTES DUE 2008

                          DATED AS OF JANUARY 29, 2003

                              THE BANK OF NEW YORK

                                     TRUSTEE

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                             CROSS-REFERENCE TABLE*

TRUST INDENTURE ACT SECTION                                   INDENTURE SECTION
---------------------------                                   -----------------
310(a)(1)..................................................          7.10
   (a)(2)..................................................          7.10
   (a)(3)..................................................          N.A.
   (a)(4)..................................................          N.A.
   (a)(5)..................................................          7.10
   (b).....................................................          7.10
   (c).....................................................          N.A.
311(a).....................................................          7.11
   (b).....................................................          7.11
   (c).....................................................          N.A.
312(a).....................................................          2.05
   (b).....................................................         13.03
   (c).....................................................         13.03
313(a).....................................................          7.06
   (b)(1)..................................................          7.06
   (b)(2)..................................................       7.06; 7.07
   (c).....................................................      7.06; 13.02
   (d).....................................................          7.06
314(a).....................................................   4.03; 4.04; 13.02;
                                                                    13.05
   (b).....................................................          N.A.
   (c)(1)..................................................         13.04
   (c)(2)..................................................         13.04
   (c)(3)..................................................          N.A.
   (d).....................................................          N.A.
   (e).....................................................         13.05
   (f).....................................................          N.A.
315(a).....................................................          7.01
   (b).....................................................      7.05; 13.02
   (c).....................................................          7.01
   (d).....................................................          7.01
   (e).....................................................          6.11
316(a)(last sentence)......................................          2.09
   (a)(1)(A)...............................................          6.05
   (a)(1)(B)...............................................          6.04
   (a)(2)..................................................          N.A.
   (b).....................................................          6.07
   (c).....................................................          N.A.
317(a)(1)..................................................          6.08
   (a)(2)..................................................          6.09
   (b).....................................................          2.04
318(a).....................................................         13.01
   (b).....................................................          N.A.
   (c).....................................................         13.01
N.A. means not applicable

----------
      *   This Cross Reference Table is not part of the Indenture.

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                                TABLE OF CONTENTS

<TABLE>
<CAPTION>
                                                                                                          PAGE
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<S>                                                                                                         <C>
ARTICLE 1 DEFINITIONS AND INCORPORATION BY REFERENCE.........................................................1

Section 1.01.       Definitions..............................................................................1
Section 1.02.       Other Definitions.......................................................................29
Section 1.03.       Incorporation by Reference of Trust Indenture Act.......................................30
Section 1.04.       Rules of Construction...................................................................30

ARTICLE 2 THE NOTES.........................................................................................31

Section 2.01.       Form and Dating.........................................................................31
Section 2.02.       Execution and Authentication............................................................32
Section 2.03.       Registrar and Paying Agent..............................................................33
Section 2.04.       Paying Agent to Hold Money in Trust.....................................................33
Section 2.05.       Holder Lists............................................................................34
Section 2.06.       Transfer and Exchange...................................................................34
Section 2.07.       Replacement Notes.......................................................................42
Section 2.08.       Outstanding Notes.......................................................................42
Section 2.09.       Treasury Notes..........................................................................43
Section 2.10.       Temporary Notes.........................................................................43
Section 2.11.       Cancellation............................................................................43
Section 2.12.       CUSIP Numbers...........................................................................43

ARTICLE 3 REDEMPTION AND PREPAYMENT.........................................................................44

Section 3.01.       Notices to Trustee......................................................................44
Section 3.02.       Selection of Notes to Be Redeemed.......................................................44
Section 3.03.       Notice of Redemption....................................................................44
Section 3.04.       Effect of Notice of Redemption..........................................................45
Section 3.05.       Deposit of Redemption Price.............................................................45
Section 3.06.       Notes Redeemed in Part..................................................................46
Section 3.07.       Optional Redemption.....................................................................46
Section 3.08.       Mandatory Redemption....................................................................46
Section 3.09.       Offer to Purchase by Application of Excess Proceeds.....................................47

ARTICLE 4 COVENANTS.........................................................................................49

Section 4.01.       Payment of Notes........................................................................49
Section 4.02.       Maintenance of Office or Agency.........................................................49
Section 4.03.       Reports.................................................................................50
Section 4.04.       Compliance Certificate..................................................................51
Section 4.05.       Taxes...................................................................................51
</TABLE>

                                       ii

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<TABLE>
<S>                                                                                                         <C>
Section 4.06.       Stay, Extension and Usury Laws..........................................................51
Section 4.07.       Restricted Payments.....................................................................52
Section 4.08.       Dividend and Other Payment Restrictions Affecting Subsidiaries..........................56
Section 4.09.       Incurrence of Indebtedness and Issuance of Preferred Stock..............................58
Section 4.10.       Asset Sales.............................................................................61
Section 4.11.       Transactions with Affiliates............................................................63
Section 4.12.       Liens...................................................................................65
Section 4.13.       Corporate Existence.....................................................................65
Section 4.14.       Offer to Repurchase Upon Change of Control..............................................65
Section 4.15.       Anti-Layering...........................................................................67
Section 4.16.       Sale and Leaseback Transactions.........................................................67
Section 4.17.       Covenant Suspension.....................................................................68
Section 4.18.       Additional Subsidiary Note Guarantees...................................................68
Section 4.19.       Designation of Restricted and Unrestricted Subsidiaries.................................69

ARTICLE 5 SUCCESSORS........................................................................................69

Section 5.01.       Merger, Consolidation, or Sale of Assets................................................69
Section 5.02.       Successor Corporation Substituted.......................................................70

ARTICLE 6 DEFAULTS AND REMEDIES.............................................................................71

Section 6.01.       Events of Default.......................................................................71
Section 6.02.       Acceleration............................................................................73
Section 6.03.       Other Remedies..........................................................................73
Section 6.04.       Waiver of Past Defaults.................................................................73
Section 6.05.       Control by Majority.....................................................................74
Section 6.06.       Limitation on Suits.....................................................................74
Section 6.07.       Rights of Holders of Notes to Receive Payment...........................................74
Section 6.08.       Collection Suit by Trustee..............................................................75
Section 6.09.       Trustee May File Proofs of Claim........................................................75
Section 6.10.       Priorities..............................................................................75
Section 6.11.       Undertaking for Costs...................................................................76

ARTICLE 7 TRUSTEE...........................................................................................76

Section 7.01.       Duties of Trustee.......................................................................76
Section 7.02.       Rights of Trustee.......................................................................77
Section 7.03.       Individual Rights of Trustee............................................................78
Section 7.04.       Trustee's Disclaimer....................................................................78
Section 7.05.       Notice of Defaults......................................................................78
Section 7.06.       Reports by Trustee to Holders of the Notes..............................................78
Section 7.07.       Compensation and Indemnity..............................................................79
Section 7.08.       Replacement of Trustee..................................................................80
Section 7.09.       Successor Trustee by Merger, etc........................................................81
</TABLE>

                                       iii

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<TABLE>
<S>                                                                                                         <C>
Section 7.10.       Eligibility; Disqualification...........................................................81
Section 7.11.       Preferential Collection of Claims Against Company.......................................81
Section 7.12.       Trustee's Application for Instructions from the Company.................................81

ARTICLE 8 LEGAL DEFEASANCE AND COVENANT DEFEASANCE..........................................................81

Section 8.01.       Option to Effect Legal Defeasance or Covenant Defeasance................................81
Section 8.02.       Legal Defeasance and Discharge..........................................................82
Section 8.03.       Covenant Defeasance.....................................................................82
Section 8.04.       Conditions to Legal or Covenant Defeasance..............................................83
Section 8.05.       Deposited Money and Government Securities to be Held in Trust; Other
                    Miscellaneous Provisions................................................................84
Section 8.06.       Repayment to Company....................................................................85
Section 8.07.       Reinstatement...........................................................................85

ARTICLE 9 AMENDMENT, SUPPLEMENT AND WAIVER..................................................................86

Section 9.01.       Without Consent of Holders of Notes.....................................................86
Section 9.02.       With Consent of Holders of Notes........................................................86
Section 9.03.       Compliance with Trust Indenture Act.....................................................88
Section 9.04.       Revocation and Effect of Consents.......................................................88
Section 9.05.       Notation on or Exchange of Notes........................................................89
Section 9.06.       Trustee to Sign Amendments, etc.........................................................89

ARTICLE 10 NOTE GUARANTEES..................................................................................89

Section 10.01.      Guarantee...............................................................................89
Section 10.02.      Subordination of Note Guarantee.........................................................90
Section 10.03.      Limitation on Guarantor Liability.......................................................90
Section 10.04.      Evidence of Note Guarantee..............................................................91
Section 10.05.      Guarantors May Consolidate, etc., on Certain Terms......................................91
Section 10.06.      Releases................................................................................92

ARTICLE 11 SUBORDINATION....................................................................................93

Section 11.01.      Agreement to Subordinate................................................................93
Section 11.02.      Liquidation; Dissolution; Bankruptcy....................................................93
Section 11.03.      Default on Designated Senior Debt.......................................................93
Section 11.04.      Acceleration of Notes...................................................................94
Section 11.05.      When Distribution Must Be Paid Over.....................................................94
Section 11.06.      Notice by Company.......................................................................95
Section 11.07.      Subrogation.............................................................................95
Section 11.08.      Relative Rights.........................................................................95
Section 11.09.      Subordination May Not Be Impaired by Company............................................96
Section 11.10.      Distribution or Notice to Representative................................................96
</TABLE>

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<TABLE>
<S>                                                                                                        <C>
Section 11.11.      Rights of Trustee and Paying Agent......................................................96
Section 11.12.      Authorization to Effect Subordination...................................................97
Section 11.13.      Amendments..............................................................................97

ARTICLE 12 SATISFACTION AND DISCHARGE.......................................................................97

Section 12.01.      Satisfaction and Discharge..............................................................97
Section 12.02.      Notices.................................................................................98

ARTICLE 13 MISCELLANEOUS....................................................................................99

Section 13.01.      Trust Indenture Act Controls............................................................99
Section 13.02.      Notices.................................................................................99
Section 13.03.      Communication by Holders of Notes with Other Holders of Notes..........................100
Section 13.04.      Certificate and Opinion as to Conditions Precedent.....................................100
Section 13.05.      Statements Required in Certificate or Opinion..........................................100
Section 13.06.      Rules by Trustee and Agents............................................................101
Section 13.07.      No Personal Liability of Directors, Officers, Employees and Stockholders...............101
Section 13.08.      Governing Law..........................................................................101
Section 13.09.      No Adverse Interpretation of Other Agreements..........................................101
Section 13.10.      Successors.............................................................................101
Section 13.11.      Severability...........................................................................102
Section 13.12.      Counterpart Originals..................................................................102
Section 13.13.      Table of Contents, Headings, etc.......................................................102
</TABLE>

                                    EXHIBITS

Exhibit A         FORM OF NOTE

Exhibit B         FORM OF SUPPLEMENTAL INDENTURE TO BE DELIVERED BY SUBSEQUENT
                  GUARANTORS

Exhibit C         INTENTIONALLY OMITTED

Exhibit D         FORM OF REGULATION S CERTIFICATE

Exhibit E         FORM OF RESTRICTED NOTES CERTIFICATE

Exhibit F         FORM OF UNRESTRICTED NOTES CERTIFICATE

                                        v

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INDENTURE dated as of January 29, 2003 among American Tower Escrow Corporation,
a Delaware corporation ("Escrow Corp.") and The Bank of New York, a New York
banking corporation, as trustee (the "Trustee") and, from and after the
consummation of the Escrow Corp. Merger (as defined in Section 1.01 hereof), the
guarantors listed on the signature pages hereto (the "Guarantors").

        Escrow Corp. and the Trustee agree as follows for the benefit of each
other and for the equal and ratable benefit of the Holders (as defined in
Section 1.01 hereof) of the 12.25% Senior Subordinated Discount Notes due 2008
(each, a "Note" and, collectively, the "Notes"):

                                   ARTICLE 1

                          DEFINITIONS AND INCORPORATION
                                  BY REFERENCE

        Section 1.01.   Definitions.

        "Accreted Value" means, as of any date of determination, an amount per
$1,000 principal amount at maturity of the Notes that is equal to the sum of (a)
the initial offering price of each Note and (b) the portion of the excess of the
principal amount at maturity of each Note over such initial offering price which
shall have been accreted thereon through such date, such amount to be so
accreted on a daily basis at a rate of 12.25% per annum of the initial offering
price of the Notes, compounded semi-annually on each February 1 and August 1
commencing on August 1, 2003 through the date of determination, computed on the
basis of a 360-day year of twelve 30-day months; provided that, at maturity, the
Accreted Value of each Note shall be equal to the principal amount of such Note.

        "Acquired Debt" means, with respect to any specified Person:

                (1)     Indebtedness of any other Person existing at the time
                        such other Person is merged with or into or became a
                        Subsidiary of such specified Person, whether or not such
                        Indebtedness is incurred in connection with, or in
                        contemplation of, such other Person merging with or
                        into, or becoming a Subsidiary of, such specified
                        Person; and

                (2)     Indebtedness secured by a Lien encumbering any asset
                        acquired by such specified Person.

        "Additional Parent Indebtedness" means (i) Indebtedness (excluding
Acquired Debt) of the Parent or shares of Disqualified Stock or preferred stock
of the Parent if the Parent at the time of incurrence of the Indebtedness or the
issuance of the Disqualified Stock or preferred stock, after giving pro forma
effect thereto as if such Indebtedness had been incurred or such Disqualified
Stock or preferred stock had been issued and the proceeds thereof had been
applied at the beginning of the applicable four-quarter period, would have had a
Debt to Adjusted Consolidated Cash Flow Ratio no greater than 7.5 to 1.0, (ii)
Acquired Debt of the Parent and

<PAGE>

(iii) Indebtedness of the Parent or shares of Disqualified Stock or preferred
stock of the Parent that is issued in exchange for, or the net proceeds of which
are used to extend, refinance, renew, replace, defease or refund any
Indebtedness or shares of Disqualified Stock or preferred stock of the Parent
described pursuant to clauses (i) or (ii) hereof.

        "Adjusted Consolidated Cash Flow" means, with respect to any Person and
as of any date of determination, the sum of:

                (1)     the Consolidated Cash Flow of such Person for the four
                        most recent full fiscal quarters ending immediately
                        prior to such date for such Person for which internal
                        financial statements are available, less such Person's
                        Tower Cash Flow for such four-quarter period; plus

                (2)     the product of four times such Person's Tower Cash Flow
                        for the most recent fiscal quarter for which internal
                        financial statements are available.

        For purposes of making the computation referred to above:

                (1)     acquisitions that have been made by such Person or any
                        of its Restricted Subsidiaries, including through
                        mergers or consolidations and including any related
                        financing transactions, during the reference period or
                        subsequent to such reference period and on or prior to
                        the calculation date shall be deemed to have occurred on
                        the first day of the reference period and Consolidated
                        Cash Flow for such reference period shall be calculated
                        without giving effect to clause (2) of the proviso set
                        forth in the definition of Consolidated Net Income;

                (2)     the Consolidated Cash Flow attributable to discontinued
                        operations, as determined in accordance with GAAP, and
                        operations or businesses disposed of prior to the
                        calculation date, shall be excluded; and

                (3)     the corporate development expense of such Person and its
                        Restricted Subsidiaries calculated in a manner
                        consistent with the audited financial statements of the
                        Parent included in the Offering Circular shall be added
                        to Consolidated Cash Flow to the extent it was included
                        in computing Consolidated Net Income.

        "Affiliate" of any specified Person means any other Person directly or
indirectly controlling or controlled by or under direct or indirect common
control with such specified Person. For purposes of this definition, "control,"
as used with respect to any Person, means the possession, directly or
indirectly, of the power to direct or cause the direction of the management or
policies of such Person, whether through the ownership of voting securities, by
agreement or otherwise; provided that beneficial ownership of 10% or more of the
Voting Stock of a Person shall be deemed to be control. No natural person who is
an executive officer or director of a Person shall, solely by virtue of such
position, be deemed to control such Person.

                                        2

<PAGE>

        "Agent" means any Registrar, co-registrar, Paying Agent or additional
paying agent.

        "Applicable Procedures" means, with respect to any transfer or exchange
of or for beneficial interests in any Global Note, the rules and procedures of
the Depositary, Euroclear and Clearstream that apply to such transfer or
exchange.

        "Asset Sale" means:

                (1)     the sale, conveyance or other disposition of any assets
                        or rights; provided that the sale, conveyance or other
                        disposition of all or substantially all of the assets of
                        the Company and its Subsidiaries taken as a whole shall
                        be governed by the provisions of Section 4.14 hereof
                        and/or the provisions of Section 5.01 hereof and not by
                        the provisions of Section 4.10 hereof; and

                (2)     the issuance of Equity Interests by any of the
                        Restricted Subsidiaries (other than directors'
                        qualifying shares or shares required by applicable law
                        to be held by a Person other than the Company, a Sister
                        Guarantor or a Restricted Subsidiary).

        Notwithstanding the preceding, none of the following items shall be
        deemed to be an Asset Sale:

                (1)     any single transaction or series of related transactions
                        that involves assets, rights or Equity Interests having
                        a fair market value of less than $1.0 million;

                (2)     a transfer of assets between or among the Company, the
                        Sister Guarantors and the Restricted Subsidiaries;

                (3)     an issuance of Equity Interests by a Restricted
                        Subsidiary to the Company, a Sister Guarantor or to
                        another Restricted Subsidiary;

                (4)     the sale, lease or other disposition of equipment,
                        inventory or accounts receivable in the ordinary course
                        of business;

                (5)     the sale or other disposition of cash or Cash
                        Equivalents;

                (6)     a transfer of Equity Interests of an Unrestricted
                        Subsidiary or an issue of Equity Interests by an
                        Unrestricted Subsidiary;

                (7)     grants of leases or licenses in the ordinary course of
                        business;

                (8)     the issuance of Equity Interests of the Company or a
                        Sister Guarantor; and

                (9)     a Restricted Payment that is permitted by Section 4.07
                        hereof or a Permitted Investment.

                                        3

<PAGE>

        "Attributable Debt" in respect of a sale and leaseback transaction
means, at the time of determination, the present value of the obligation of the
lessee for net rental payments during the remaining term of the lease included
in such sale and leaseback transaction including any period for which such lease
has been extended or may, at the option of the lessor, be extended. Such present
value shall be calculated using a discount rate equal to the rate of interest
implicit in such transaction, determined in accordance with GAAP.

        "Bankruptcy Law" means Title 11, U.S. Code or any similar federal or
state law for the relief of debtors.

        "Beneficial Owner" has the meaning assigned to such term in Rule 13d-3
and Rule 13d-5 under the Exchange Act, except that in calculating the beneficial
ownership of any particular "person" (as that term is used in Section 13(d)(3)
of the Exchange Act), such "person" shall be deemed to have beneficial ownership
of all securities that such "person" has the right to acquire by conversion or
exercise of other securities, whether such right is currently exercisable or is
exercisable only upon the occurrence of a subsequent condition. The terms
"Beneficially Owns" and "Beneficially Owned" have a corresponding meaning.

        "Board of Directors" means:

                (1)     with respect to a corporation, the board of directors
                        (or its executive committee) of the corporation;

                (2)     with respect to a partnership, the board of directors of
                        the general partner (if a corporation) of the
                        partnership; and

                (3)     with respect to any other Person, the board or committee
                        of such Person serving a similar function.

        "Business Day" means any day other than a Legal Holiday.

        "Capital Lease Obligation" means, at the time any determination is to be
made, the amount of the liability in respect of a capital lease that would at
that time be required to be capitalized on a balance sheet in accordance with
GAAP.

        "Capital Stock" means:

                (1)     in the case of a corporation, corporate stock;

                (2)     in the case of an association or business entity, any
                        and all shares, interests, participations, rights or
                        other equivalents (however designated) of corporate
                        stock;

                (3)     in the case of a partnership or limited liability
                        company, partnership or membership interests (whether
                        general or limited); and

                                        4

<PAGE>

                (4)     any other interest or participation that confers on a
                        Person the right to receive a share of the profits and
                        losses of, or distributions of assets of, the issuing
                        Person.

        "Cash Equivalents" means:

                (1)     marketable, direct obligations of the United States of
                        America, its agencies and instrumentalities maturing
                        within 365 days of the date of purchase;

                (2)     commercial paper and other short-term obligations of
                        business savings accounts issued by corporations, each
                        of which shall have a combined net worth of at least
                        $100,000,000 and each of which conducts a substantial
                        part of its business in the United States of America,
                        maturing within 270 days from the date of original issue
                        thereof, and whose issuer is, at the time of purchase,
                        rated "P-2" or better by Moody's or "A-2" or better by
                        S&P ;

                (3)     repurchase agreements, bankers' acceptances and domestic
                        and Eurodollar certificates of deposit maturing within
                        365 days of the date of purchase which are issued by, or
                        time deposits maintained with

                        (a)     a United States national or state bank (or any
                                domestic branch of a foreign bank) subject to
                                supervision and examination by federal or state
                                banking or depository institution authorities
                                and having capital, surplus and undivided
                                profits totaling more than $100,000,000 and
                                rated "A" or better by Moody's or S&P,

                        (b)     a broker/dealer (acting as principal) registered
                                as a broker or a dealer under Section 15 of the
                                Exchange Act the unsecured short-term debt
                                obligations of which are rated "P-1" by Moody's
                                and at least "A-1" by S&P at the date of
                                purchase, or

                        (c)     an unrated broker/dealer, acting as principal,
                                that is a Wholly Owned Restricted Subsidiary
                                (but substituting "Subsidiary" for "Restricted
                                Subsidiary" in the definition thereof) of a
                                non-bank or bank holding company, the unsecured
                                short-term debt obligations of which are rated
                                "P-1" by Moody's and at least "A-1" by S&P at
                                the date of purchase; and

                (4)     money market funds having a rating from Moody's and S&P
                        in the highest investment category granted thereby.

        "Change of Control" means the occurrence of any of the following:

                (1)     the sale, lease, transfer, conveyance or other
                        disposition (other than by way of merger or
                        consolidation), in one or a series of related
                        transactions,

                                        5

<PAGE>

                        of all or substantially all of the assets of the Company
                        and its Restricted Subsidiaries, taken as a whole, to
                        any "person" (as such term is used in Section 13(d)(3)
                        of the Exchange Act) other than the Principal or a
                        Related Party of the Principal;

                (2)     the adoption of a plan relating to the liquidation or
                        dissolution of the Company;

                (3)     the consummation of any transaction (including, without
                        limitation, any merger or consolidation) the result of
                        which is that any "person" (as defined above), other
                        than the Principal and his Related Parties or a
                        Subsidiary of the Parent, Beneficially Owns (i) 35% or
                        more of the Voting Stock of the Company (measured by
                        voting power rather than number of shares) if the
                        Company is not a Subsidiary of any Person or, if the
                        Company is a Subsidiary of any Person, of the ultimate
                        parent entity of which the Company is a Subsidiary, and
                        (ii) a greater percentage of such Voting Stock (measured
                        by voting power rather than number of shares) than the
                        Principals and their Related Parties; or

                (4)     the first day on which a majority of the members of the
                        Board of Directors of the Company are not Continuing
                        Directors.

        "Clearstream" means Clearstream Banking S.A. (or any successor
securities clearing agency).

        "Company" means, prior to the consummation of the Escrow Corp. Merger,
American Tower Escrow Corporation, and after the consummation of the Escrow
Corp. Merger, American Towers, Inc.

        "Consolidated" means (i) when used with respect to the Parent, the
consolidated financial position and results of operations of the Parent, the
Company, the Sister Guarantors and the Restricted Subsidiaries (excluding any
other Subsidiaries of the Parent and notwithstanding any reference to such
Subsidiaries in any other definition) and (ii) when used with respect to any
other Person, the consolidated financial position and results of operations of
such Person and its Restricted Subsidiaries.

        "Consolidated Cash Flow" means, with respect to any Person for any
period, the Consolidated Net Income of such Person for such period; plus

                (1)     provision for taxes based on income or profits of such
                        Person and its Restricted Subsidiaries for such period,
                        to the extent that such provision for taxes was included
                        in computing such Consolidated Net Income; plus

                (2)     consolidated interest expense of such Person and its
                        Restricted Subsidiaries for such period, whether paid or
                        accrued and whether or not capitalized (including,
                        without limitation, amortization of debt issuance

                                        6

<PAGE>

                        costs and original issue discount, non-cash interest
                        payments, the interest component of any deferred payment
                        obligations, the interest component of all payments
                        associated with Capital Lease Obligations, commissions,
                        discounts and other fees and charges incurred in respect
                        of letters of credit or bankers' acceptance financings,
                        and net payments (if any) pursuant to Hedging
                        Obligations), to the extent that any such expense was
                        deducted in computing such Consolidated Net Income; plus

                (3)     depreciation, amortization (including amortization of
                        goodwill and other intangibles) and other non-cash
                        expenses (including write-offs or write-downs of
                        goodwill and other intangible assets but excluding any
                        such non-cash expense to the extent that it represents
                        an accrual of or reserve for cash expenses in any future
                        period) of such Person and its Restricted Subsidiaries
                        for such period to the extent that such depreciation,
                        amortization and other non-cash expenses were deducted
                        in computing such Consolidated Net Income; minus

                (4)     non-cash items increasing such Consolidated Net Income
                        for such period (excluding any items that were accrued
                        in the ordinary course of business),

in each case, on a consolidated basis and determined in accordance with GAAP.

        "Consolidated Indebtedness" means, with respect to any Person as of any
date of determination, the sum, without duplication, of:

                (1)     the total amount of Indebtedness of such Person and its
                        Restricted Subsidiaries; plus

                (2)     the total amount of Indebtedness of any other Person, to
                        the extent that such Indebtedness has been Guaranteed by
                        the referent Person or one or more of its Restricted
                        Subsidiaries; plus

                (3)     the aggregate liquidation value of all Disqualified
                        Stock of such Person and all preferred stock of
                        Restricted Subsidiaries of such Person,

in each case, determined on a consolidated basis in accordance with GAAP.

        "Consolidated Interest Expense" means, with respect to any Person for
any period:

                (1)     the consolidated interest expense of such Person and its
                        Restricted Subsidiaries for such period determined in
                        accordance with GAAP, whether paid or accrued and
                        whether or not capitalized (including, without
                        limitation, amortization of debt issuance costs and
                        original issue discount, non-cash interest payments, the
                        interest component of any deferred payment obligations,
                        the interest component of all payments associated with
                        Capital Lease Obligations, commissions, discounts and
                        other fees and

                                        7

<PAGE>

                        charges incurred in respect of letter of credit or
                        bankers' acceptance financings, and net payments, if
                        any, pursuant to Hedging Obligations); plus

                (2)     all preferred stock dividends paid or accrued in respect
                        of such Person's and its Restricted Subsidiaries'
                        preferred stock to Persons other than such Person or its
                        Wholly Owned Restricted Subsidiaries of other than
                        preferred stock dividends paid by such Person in shares
                        of preferred stock that is not Disqualified Stock.

        "Consolidated Net Income" means, with respect to any specified Person
for any period, the aggregate of the Net Income of such Person and its
Restricted Subsidiaries for such period, on a consolidated basis, determined in
accordance with GAAP; provided that:

                (1)     the Net Income of any Person (other than the specified
                        Person) that is not a Restricted Subsidiary or that is
                        accounted for by the equity method of accounting shall
                        be included only to the extent of the amount of
                        dividends or distributions paid in cash to the specified
                        Person or a Restricted Subsidiary thereof and shall not
                        be included if a net loss;

                (2)     the Net Income (and net loss) of any Person acquired in
                        a pooling of interests transaction for any period prior
                        to the date of such acquisition shall be excluded;

                (3)     the cumulative effect of a change in accounting
                        principles shall be excluded; and

                (4)     the Net Income (and net loss) of any Unrestricted
                        Subsidiary shall be excluded whether or not distributed
                        to such specified Person or one of its Restricted
                        Subsidiaries.

        "Consolidated Tangible Assets" means, with respect to a specified
Person, the total consolidated assets of such Person and its Restricted
Subsidiaries, less the total intangible assets of such Person and its Restricted
Subsidiaries, as shown on the most recent internal consolidated balance sheet of
such Person and such Restricted Subsidiaries calculated on a consolidated basis
in accordance with GAAP.

        "Continuing Directors" means, as of any date of determination, any
member of the Board of Directors of the Company who:

                (1)     was a member of such Board of Directors on the Issue
                        Date;

                (2)     was nominated for election or elected to such Board of
                        Directors with the approval of a majority of the
                        Continuing Directors who were members of such Board at
                        the time of such nomination or election; or

                                        8

<PAGE>

                (3)     is a designee of the Principal or was nominated by the
                        Principal.

        "Convertible Notes" mean, collectively, (a) the $300,000,000.00 6.25%
Convertible Notes Due 2009 issued pursuant to that certain indenture dated
October 4, 1999 of the Parent with The Bank of New York as trustee, (b) the
$425,500,000.00 2.25% Convertible Notes Due 2009 issued pursuant to that certain
indenture dated October 4, 1999 of the Parent with The Bank of New York as
trustee and (c) the $450,000,000.00 5.00% Convertible Notes Due 2010 issued
pursuant to that certain indenture dated February 15, 2000 of the Parent with
The Bank of New York as trustee.

        "Corporate Trust Office of the Trustee" shall be at the address of the
Trustee specified in Section 13.02 hereof or such other address as to which the
Trustee may give notice to the Company.

        "Credit Agreement" means that certain Amended and Restated Loan
Agreement, dated as of January 6, 2000, by and among The Toronto Dominion Bank,
New York Branch, as Issuing Bank, Toronto Dominion (Texas), Inc., as
Administrative Agent, the several lenders and other agents party thereto and
American Tower, L.P., American Towers, Inc., Towersites Monitoring, Inc. and
American Tower International, Inc., as borrowers, including any related notes,
Guarantees, collateral documents, instruments and agreements executed in
connection therewith, in each case, as amended, supplemented, restated,
modified, renewed, refunded, replaced or refinanced in whole or in part from
time to time, including to permit an increase in borrowings thereunder.

        "Credit Facilities" means one or more debt, commercial paper or
securitization facilities or financings (including, without limitation, the
Credit Agreement), in each case, as amended, supplemented, restated, modified,
renewed, refunded, replaced or refinanced in whole or in part from time to time,
including to permit an increase in borrowings thereunder.

        "Custodian" means the Trustee, as custodian with respect to the Notes in
global form, or any successor entity thereto.

        "Debt to Adjusted Consolidated Cash Flow Ratio" means, with respect to
any Person and as of any date of determination, the ratio of:

                (1)     the Consolidated Indebtedness of such Person as of such
                        date to

                (2)     the Adjusted Consolidated Cash Flow of such Person as of
                        such date.

        "Default" means any event that is, or with the passage of time or the
giving of notice or both would be, an Event of Default.

        "Definitive Note" means a certificated Note registered in the name of
the Holder thereof and issued in accordance with Section 2.06 hereof,
substantially in the form of Exhibit A hereto except that such Note shall not
bear the Global Note Legend and shall not have the "Schedule of Exchanges of
Interests in the Global Note" attached thereto.

                                        9

<PAGE>

        "Depositary" means, with respect to the Notes issuable or issued in
whole or in part in global form, the Person specified in Section 2.03 hereof as
the Depositary with respect to the Notes, and any and all successors thereto
appointed as depositary hereunder and having become such pursuant to the
applicable provision of this Indenture.

        "Designated Senior Debt" means:

                (1)     any Indebtedness outstanding under the Credit Agreement;
                        and

                (2)     after payment in full of all Obligations under the
                        Credit Agreement, any other Senior Debt permitted under
                        this Indenture the principal amount of which is $25.0
                        million or more and that has been designated by the
                        Company as "Designated Senior Debt."

        "Disqualified Stock" means any Capital Stock that, by its terms (or by
the terms of any security into which it is convertible, or for which it is
exchangeable, in each case at the option of the holder of the Capital Stock), or
upon the happening of any event, matures or is mandatorily redeemable, pursuant
to a sinking fund obligation or otherwise, or redeemable at the option of the
holder of the Capital Stock, in whole or in part, on or prior to the date that
is 91 days after the date on which the Notes mature. Notwithstanding the
preceding sentence, any Capital Stock that would constitute Disqualified Stock
solely because the holders of the Capital Stock have the right to require the
Company to repurchase such Capital Stock upon the occurrence of a Change of
Control or an Asset Sale shall not constitute Disqualified Stock if the terms of
such Capital Stock provide that the Company may not repurchase or redeem any
such Capital Stock pursuant to such provisions unless such repurchase or
redemption complies with Section 4.07 hereof.

        "Effectiveness Target Date" shall have the meaning set forth in Section
6(a)(iii) of the Registration Rights Agreement.

        "Equity Interests" means Capital Stock and all warrants, options or
other rights to acquire Capital Stock (but excluding any debt security that is
convertible into, or exchangeable for, Capital Stock).

        "Escrow Account" means the escrow account for the deposit of
approximately $432.7 million, which represents 101% of the Accreted Value of the
Notes on March 30, 2003 to be held in escrow under the Escrow Agreement pending
consummation of the Escrow Corp. Merger or a mandatory redemption of the Notes
as described in Section 3.08 hereof.

        "Escrow Agreement" means the Escrow and Disbursement Agreement, dated
the Issue Date, among Escrow Corp., the Trustee and The Bank of New York, as
escrow agent governing the disbursement of funds from the Escrow Account, as
amended from time to time in accordance with this Indenture.

        "Escrow Corp." means American Tower Escrow Corporation, a Delaware
corporation.

                                       10

<PAGE>

        "Escrow Corp. Merger" means the merger transaction involving Escrow
Corp. and American Towers, Inc. pursuant to the Escrow Corp. Merger Agreement.

        "Escrow Corp. Merger Agreement" means an Agreement and Plan of Merger
with respect to the Escrow Crop. Merger, dated as of the Issue Date.

        "Euroclear" means Euroclear Bank S.A./N.V., as operator of the Euroclear
system (or any successor securities clearing agency).

        "Exchange Act" means the Securities Exchange Act of 1934, as amended.

        "Exchange Note" means any Note issued in exchange for an Original Note
or Original Notes pursuant to the Exchange Offer or otherwise registered under
the Securities Act and any Note with respect to which the next preceding
Predecessor Note of such Note was an Exchange Note.

        "Exchange Offer" has the meaning set forth in the form of Note attached
as Exhibit A.

        "Exchange Registration Statement" has the meaning set forth in the form
of Note attached as Exhibit A.

        "Excluded International Sale" means an issue, sale or other disposition
of Capital Stock of a Restricted Subsidiary of the Company or a Sister Guarantor
the principal operations of which are conducted, and the principal assets of
which are located, outside the United States, so long as after giving effect
thereto such Restricted Subsidiary would remain a Restricted Subsidiary of the
Company or a Sister Guarantor.

        "Existing Indebtedness" means Indebtedness of the Company, the Sister
Guarantors and their Subsidiaries (other than Indebtedness under the Credit
Agreement) in existence on the Issue Date, until such amounts are repaid.

        "Existing Parent Indebtedness" means the Senior Notes Due 2009 and the
Convertible Notes and any Indebtedness of the Parent issued in exchange for, or
the net proceeds of which are used to extend, refinance, renew, replace, defease
or refund any such Indebtedness which meets the conditions for Permitted
Refinancing Indebtedness set forth in clauses (1) and (2) of the definition
thereof.

        "GAAP" means generally accepted accounting principles in the United
States set forth in the opinions and pronouncements of the Accounting Principles
Board of the American Institute of Certified Public Accountants and statements
and pronouncements of the Financial Accounting Standards Board or in such other
statements by such other entity as have been approved by a significant segment
of the accounting profession, which are in effect on the Issue Date.

        "Global Notes" means, the global Notes, substantially in the form of
Exhibit A hereto.

                                       11

<PAGE>

        "Global Note Legend" means the legend set forth in Section 2.06(f)(i),
which is required to be placed on all Global Notes issued under this Indenture.

        "Government Securities" means direct obligations of, or obligations
guaranteed by, the United States of America, and the payment for which the
United States pledges its full faith and credit.

        "Group Guarantors" means, upon the consummation of the Escrow Corp.
Merger, each of the Guarantors other than the Parent.

        "Guarantee" means a guarantee other than by endorsement of negotiable
instruments for collection in the ordinary course of business, direct or
indirect, in any manner including, without limitation, by way of a pledge of
assets or through letters of credit or reimbursement agreements in respect
thereof, of all or any part of any Indebtedness.

        "Guarantors" means, upon the consummation of the Escrow Corp. Merger,
each of:

                (1)     the Wholly Owned Domestic Restricted Subsidiaries of the
                        Company;

                (2)     the Sister Guarantors;

                (3)     the Wholly Owned Domestic Restricted Subsidiaries of the
                        Sister Guarantors;

                (4)     any other Subsidiary of the Company or any of the Sister
                        Guarantors that executes a Note Guarantee pursuant to
                        Section 4.18 hereof; and

                (5)     the Parent;

and their respective successors and assigns unless or until released as provided
for in Section 10.6 hereof. Prior to the consummation of the Escrow Corp.
Merger, there shall be no Guarantor.

        "Hedging Obligations" means, with respect to any specified Person, the
obligations of such Person under:

                (1)     interest rate swap agreements, interest rate cap
                        agreements and interest rate collar agreements; and

                (2)     other agreements or arrangements designed to protect
                        such Person against fluctuations in interest rates or
                        currency exchange rates.

        "Holder" means a Person in whose name a Note is registered.

        "Indebtedness" means, with respect to any specified Person, any
indebtedness of such Person, whether or not contingent:

                                       12

<PAGE>

                (1)     in respect of borrowed money;

                (2)     evidenced by bonds, notes, debentures or similar
                        instruments or letters of credit (or reimbursement
                        agreements in respect thereof);

                (3)     in respect of banker's acceptances;

                (4)     representing Capital Lease Obligations;

                (5)     representing the balance deferred and unpaid of the
                        purchase price of any property, except any such balance
                        that constitutes an accrued expense or trade payable; or

                (6)     representing any Hedging Obligations,

if and to the extent any of the preceding items (other than letters of credit
and Hedging Obligations) would appear as a liability upon a balance sheet of the
specified Person prepared in accordance with GAAP. In addition, the term
"Indebtedness" includes all Indebtedness of others secured by a Lien on any
asset of the specified Person whether or not such Indebtedness is assumed by the
specified Person (the amount of such Indebtedness as of any date being deemed to
be the lesser of the value of such property or assets as of such date or the
principal amount of such Indebtedness of such other Person so secured) and, to
the extent not otherwise included, the Guarantee by the specified Person of any
Indebtedness of any other Person.

        The amount of any Indebtedness outstanding as of any date shall be:

                (1)     the accreted value of the Indebtedness, in the case of
                        any Indebtedness issued with original issue discount;
                        and

                (2)     the principal amount of the Indebtedness, together with
                        any interest on the Indebtedness that is more than 30
                        days past due, in the case of any other Indebtedness.

        "Indenture" means this Indenture, as amended or supplemented from time
to time.

        "Indirect Participant" means a Person who holds a beneficial interest in
a Global Note through a Participant.

        "Investment Grade Rating" means a rating equal to or higher than Baa3
(or the equivalent) by Moody's and BBB- (or the equivalent) by S&P (or, if
either such entity ceases to rate the Notes for reasons outside of the control
of the Company, the equivalent investment grade credit rating from any other
"nationally recognized statistical rating organization" within the meaning of
Rule 15c3-1(c)(2)(vi)(F) under the Exchange Act selected by the Company as a
replacement agency, if any such agency exists at such time).

                                       13

<PAGE>

        "Investments" means, with respect to any Person, all direct or indirect
investments by such Person in other Persons (including Affiliates) in the forms
of loans (including Guarantees of Indebtedness or other obligations), advances
or capital contributions (excluding commission, travel and similar advances to
officers and employees made in the ordinary course of business), purchases or
other acquisitions for consideration of Indebtedness, Equity Interests or other
securities, together with all items that are or would be classified as
investments on a balance sheet prepared in accordance with GAAP. If such Person
or any of its Restricted Subsidiaries sells or otherwise disposes of any Equity
Interests of any direct or indirect Restricted Subsidiary of such Person such
that, after giving effect to any such sale or disposition, it is no longer a
Restricted Subsidiary of such Person, such Person shall be deemed to have made
an Investment on the date of any such sale or disposition equal to the fair
market value of such Person's Investments in such Subsidiary that were not sold
or disposed of in an amount determined as provided in the final paragraph of
Section 4.07 hereof.

        "Issue Date" means the date on which the Original Notes are first
authenticated and delivered under this Indenture.

        "Legal Holiday" means a Saturday, a Sunday or a day on which banking
institutions in The City of New York or at a place of payment are authorized by
law, regulation or executive order to remain closed.

        "Licenses" means, collectively, any telephone, microwave, radio
transmissions, personal communications or other license, authorization,
certificate of compliance, franchise, approval or permit, whether for the
construction, the ownership or the operation of any communications tower
facilities, granted or issued by the Federal Communications Commission (or other
similar or successor agency of the federal government administering the
Communications Act of 1934 or any similar or successor federal statute) and held
by the Company, the Sister Guarantors or any of the Restricted Subsidiaries.

        "Lien" means, with respect to any asset, any mortgage, lien, pledge,
charge, security interest or encumbrance of any kind in respect of such asset,
whether or not filed, recorded or otherwise perfected under applicable law,
including any conditional sale or other title retention agreement, any lease in
the nature thereof, any option or other agreement to sell or give a security
interest in and any filing of or agreement to give any financing statement under
the Uniform Commercial Code (or equivalent statutes) of any jurisdiction.

        "Liquidated Damages" means all liquidated damages then owing pursuant to
Section 6 of the Registration Rights Agreement.

        "Moody's" means Moody's Investors Service, Inc. or any successor to the
rating agency business thereof.

        "Net Income" means, with respect to any Person, the net income (loss) of
such Person, determined in accordance with GAAP and before any reduction in
respect of preferred stock dividends, excluding, however:

                                       14

<PAGE>

        (1)     any gain or loss, together with any related provision for taxes
                on such gain or loss, realized in connection with:

                (a)     any Asset Sale (including, without limitation,
                        dispositions pursuant to sale and leaseback
                        transactions); or

                (b)     the disposition of any securities by such Person or any
                        of its Restricted Subsidiaries or the extinguishment of
                        any Indebtedness of such Person or any of its Restricted
                        Subsidiaries; and

        (2)     any extraordinary gain or loss, together with any related
                provision for taxes on such extraordinary gain or loss.

        "Net Proceeds" means the aggregate cash proceeds received by the
Company, any Sister Guarantor or any of the Restricted Subsidiaries in respect
of any Asset Sale (including, without limitation, any cash received upon the
sale or other disposition of any non-cash consideration received in any Asset
Sale), net of:

                (1)     the direct costs relating to such Asset Sale (including,
                        without limitation, legal, accounting and investment
                        banking fees, sales commissions and finders', brokers'
                        or similar fees) and any relocation or severance
                        expenses incurred as a result thereof;

                (2)     taxes paid or payable as a result thereof (after taking
                        into account any available tax credits or deductions and
                        any tax sharing arrangements);

                (3)     amounts required to be applied to the repayment of
                        Indebtedness (other than Senior Debt) secured by a Lien
                        on the asset or assets that were the subject of such
                        Asset Sale;

                (4)     all distributions and other payments required to be made
                        to minority interest holders in Restricted Subsidiaries
                        as a result of such Asset Sale;

                (5)     the deduction of appropriate amounts provided by the
                        seller as a reserve in accordance with GAAP against any
                        liabilities associated with the assets disposed of in
                        such Asset Sale and retained by the Company, any Sister
                        Guarantor or any Restricted Subsidiary after such Asset
                        Sale; and

                (6)     without duplication, any reserves that the Company's
                        Board of Directors determines in good faith should be
                        made in respect of the sale price of such asset or
                        assets for post closing adjustments;

provided that in the case of any reversal of any reserve referred to in clause
(5) or (6) above, the amount so reversed shall be deemed to be Net Proceeds from
an Asset Sale as of the date of such reversal.

                                       15

<PAGE>

        "Non-Recourse Debt" means Indebtedness:

                (1)     as to which none of the Company, any Sister Guarantor or
                        any of the Restricted Subsidiaries (a) provides credit
                        support of any kind (including any undertaking,
                        agreement or instrument that would constitute
                        Indebtedness) or (b) is directly or indirectly liable as
                        a guarantor or otherwise;

                (2)     no default with respect to which (including any rights
                        that the holders of the Indebtedness may have to take
                        enforcement action against an Unrestricted Subsidiary)
                        would permit upon notice, lapse of time or both any
                        holder of any other Indebtedness of the Company, any
                        Sister Guarantor or any of the Restricted Subsidiaries
                        to declare a default on such other Indebtedness or cause
                        the payment of the Indebtedness to be accelerated or
                        payable prior to its stated maturity; and

                (3)     as to which the lenders have been notified in writing
                        that they shall not have any recourse to the stock or
                        assets of the Company, any Sister Guarantor or any of
                        the Restricted Subsidiaries.

        "Non-Tower Cash Flow" means, with respect to any Person and as of any
date of determination, the Consolidated Cash Flow of such Person and its
Restricted Subsidiaries for the four most recent full fiscal quarters ending
immediately prior to such date for which internal financial statements are
available that is not included in Tower Cash Flow of such Person, all determined
on a consolidated basis and in accordance with GAAP. Non-Tower Cash Flow of such
Person shall not include revenues derived from asset sales, other than sales or
other dispositions of inventory in the ordinary course of business.

        "Notes" has the meaning assigned to it in the preamble to this Indenture
and includes the Exchange Notes and the Original Notes.

        "Note Guarantee" means the Guarantee by each Guarantor of the Company's
payment obligations under this Indenture and the Notes, as provided pursuant to
Article 10 of this Indenture.

        "Obligations" means any principal, interest, penalties, fees,
indemnifications, reimbursements, damages and other liabilities payable under
the documentation governing any Indebtedness.

        "Offering" means the private offering of the Notes by the Company.

        "Offering Circular" means the Confidential Offering Circular, dated
January 22, 2003, including the documents incorporated by reference therein,
relating to the private offering of the Original Notes and the Warrants.

                                       16

<PAGE>

        "Officer" means, with respect to any Person, the Chairman of the Board,
the Chief Executive Officer, the President, the Chief Operating Officer, the
Chief Financial Officer, the Treasurer, any Assistant Treasurer, the Controller,
the Secretary or any Vice-President of such Person.

        "Officers' Certificate" means a certificate signed on behalf of the
Company by two Officers of the Company, one of whom must be the principal
executive officer, the principal financial officer, the treasurer or the
principal accounting officer of the Company, that meets the requirements of
Section 13.04 hereof.

        "Opinion of Counsel" means an opinion from legal counsel that meets the
requirements of Section 13.04 hereof. The counsel may be an employee of or
counsel to the Company or any Subsidiary of the Company.

        "Parent" means American Tower Corporation, a Delaware corporation.

        "Participant" means, with respect to the Depositary, Euroclear or
Clearstream, a Person who has an account with the Depositary, Euroclear or
Clearstream, respectively (and, with respect to DTC, shall include Euroclear and
Clearstream).

        "Permitted Business" means any business of the type conducted by the
Parent or its Subsidiaries on the Issue Date and any other business related,
ancillary or complementary to any such business.

        "Permitted Investment" means:

                (1)     any Investment in the Company, any Sister Guarantor or
                        any Restricted Subsidiary;

                (2)     any Investment in Cash Equivalents;

                (3)     any Investment by the Company, any Sister Guarantor or
                        any Restricted Subsidiary in a Person, if as a result of
                        such Investment:

                        (a)     such Person becomes a Restricted Subsidiary; or

                        (b)     such Person is merged, consolidated or
                                amalgamated with or into, or transfers or
                                conveys substantially all of its assets to, or
                                is liquidated into, the Company, any Sister
                                Guarantor or any Restricted Subsidiary;

                (4)     any Investment by the Company, any Sister Guarantor or
                        any Restricted Subsidiary that

                        (a)     is in substance the acquisition of a class of
                                Capital Stock of a Restricted Subsidiary (the
                                "Target"),

                                       17

<PAGE>

                        (b)     increases the percentage of one or more classes
                                of Capital Stock of the Target beneficially
                                owned by the Company, the Sister Guarantors and
                                the Restricted Subsidiaries,

                        (c)     does not decrease the percentage of the total
                                voting power of shares of Capital Stock of the
                                Target entitled (without regard to the
                                occurrence of any contingency) to vote in the
                                election of directors, managers or trustees of
                                the Target that is owned by the Company, the
                                Sister Guarantors and the Restricted
                                Subsidiaries, and

                        (d)     does not decrease the percentage of
                                stockholders' equity (including stock subject to
                                mandatory redemption) of the Target, as
                                reflected on its most recent internal balance
                                sheet prepared in accordance with GAAP,
                                available upon liquidation of the Target to
                                Capital Stock of the Target owned by the
                                Company, the Sister Guarantors and the
                                Restricted Subsidiaries;

                (5)     any Investment made as a result of the receipt of
                        non-cash consideration from an Asset Sale that was made
                        pursuant to and in compliance with Section 4.10 hereof;

                (6)     any acquisition of assets solely in exchange for the
                        issuance of Equity Interests (other than Disqualified
                        Stock) of the Company or a Sister Guarantor;

                (7)     receivables created in the ordinary course of business;

                (8)     loans or advances to employees made in the ordinary
                        course of business since the Issue Date not to exceed
                        $5.0 million at any one time outstanding;

                (9)     securities and other assets received in settlement of
                        trade debts or other claims arising in the ordinary
                        course of business;

                (10)    Investments since the Issue Date of up to an aggregate
                        of $100.0 million at any one time outstanding (each such
                        Investment being measured as of the date made and
                        without giving effect to subsequent changes in value);

                (11)    Investments in Verestar and its Subsidiaries since the
                        Issue Date of up to an aggregate amount of $25.0 million
                        at any one time outstanding (each such Investment being
                        measured as of the date made and without giving effect
                        to subsequent changes in value); and

                (12)    other Investments in Permitted Businesses since the
                        Issue Date not to exceed an amount equal to $10.0
                        million plus 10% of the Consolidated Tangible Assets of
                        the Company and the Sister Guarantors (on a combined

                                       18

<PAGE>

                        basis) at any one time outstanding (each such Investment
                        being measured as of the date made and without giving
                        effect to subsequent changes in value).

        "Permitted Junior Securities" means:

                (1)     Equity Interests in the Company or any Guarantor; or

                (2)     debt securities that are subordinated to all Senior Debt
                        and any debt securities issued in exchange for Senior
                        Debt to substantially the same extent as, or to a
                        greater extent than, the Notes and the Note Guarantees
                        are subordinated to Senior Debt under this Indenture.

        "Permitted Liens" means:

                (1)     Liens securing Senior Debt of the Company or the
                        Guarantors;

                (2)     Liens securing any Indebtedness of any of the Restricted
                        Subsidiaries that are not Guarantors that was permitted
                        by the terms of this Indenture to be incurred;

                (3)     Liens in favor of the Company or a Sister Guarantor;

                (4)     Liens existing on the Issue Date and renewals and
                        replacements thereof to the extent they secure Permitted
                        Refinancing Indebtedness;

                (5)     Liens for taxes, assessments or governmental charges or
                        claims that are not yet delinquent or that are being
                        contested in good faith by appropriate proceedings
                        promptly instituted and diligently concluded; provided
                        that any reserve or other appropriate provision as shall
                        be required in conformity with GAAP shall have been made
                        therefor;

                (6)     Liens of carriers, warehousemen, mechanics, vendors
                        (solely to the extent arising by operation of law),
                        laborers and materialmen incurred in the ordinary course
                        of business for sums not yet due or being diligently
                        contested in good faith, if reserves or appropriate
                        provisions shall have been made therefor;

                (7)     Liens incurred in the ordinary course of business in
                        connection with worker's compensation and unemployment
                        insurance, social security obligations, assessments or
                        government charges which are not overdue for more than
                        60 days;

                (8)     restrictions on the transfer of Licenses or assets of
                        the Company, any Sister Guarantor or any of the
                        Restricted Subsidiaries imposed by any of the Licenses
                        as in effect on the Issue Date or imposed by the

                                       19

<PAGE>

                        Communications Act of 1934, any similar or successor
                        federal statute or the rules and regulations of the
                        Federal Communications Commission (or other similar or
                        successor agency of the federal government administering
                        such Act or successor statute) thereunder, all as the
                        same may be in effect from time to time;

                (9)     Liens arising by operation of law in favor of purchasers
                        in connection with the sale of an asset; provided,
                        however, that such Lien only encumbers the property
                        being sold;

                (10)    Liens to secure performance of statutory obligations,
                        surety or appeal bonds, performance bonds, bids or
                        tenders;

                (11)    judgment Liens which do not result in an Event of
                        Default;

                (12)    Liens in connection with escrow deposits made in
                        connection with any acquisition of assets;

                (13)    Liens securing Indebtedness permitted to be incurred
                        under clauses (4) and (7) of the second paragraph of
                        Section 4.09 hereof;

                (14)    easements, rights-of-way, zoning restrictions, licenses
                        or restrictions on use and other similar encumbrances on
                        the use of real property that:

                        (a)     are not incurred in connection with the
                                borrowing of money or the obtaining of advances
                                or credit (other than trade credit in the
                                ordinary course of business); and

                        (b)     do not in the aggregate materially detract from
                                the value of the property or materially impair
                                the use thereof in the operation of business by
                                the Company, the Sister Guarantors and the
                                Restricted Subsidiaries;

                (15)    Liens on property of the Company, a Sister Guarantor or
                        a Restricted Subsidiary at the time the Company, a
                        Sister Guarantor or Restricted Subsidiary acquired the
                        property, including acquisition by means of a merger or
                        consolidation with or into the Company, a Sister
                        Guarantor or any Restricted Subsidiary, provided,
                        however, that such Liens are not created, incurred or
                        assumed in connection with or in contemplation of such
                        acquisition, and provided further that such Liens may
                        not extend to any other property owned by the Company,
                        any Sister Guarantor or any Restricted Subsidiary; and

                (16)    Liens securing Indebtedness in an aggregate principal
                        amount at any time outstanding that, together with any
                        Attributable Debt, does not exceed 10% of:

                                       20

<PAGE>

                        (a)     Consolidated Tangible Assets of the Company and
                                the Sister Guarantors (on a combined basis),
                                reduced by

                        (b)     the amount of current liabilities (excluding
                                current maturities of long-term debt) of the
                                Company, the Sister Guarantors and the
                                Restricted Subsidiaries, further reduced by

                        (c)     appropriate adjustments on account of minority
                                interests in Restricted Subsidiaries held by
                                Persons other than the Company, a Sister
                                Guarantor and the Restricted Subsidiaries,

                        all as shown on the most recent internal consolidated
                        balance sheet of the Company and its Restricted
                        Subsidiaries and each Sister Guarantor and its
                        Restricted Subsidiaries calculated on a combined basis
                        in accordance with GAAP.

        "Permitted Refinancing Indebtedness" means any Indebtedness of the
Company, any Sister Guarantor or any of the Restricted Subsidiaries issued in
exchange for, or the net proceeds of which are used to extend, refinance, renew,
replace, defease or refund other Indebtedness of the Company, any Sister
Guarantor or any of the Restricted Subsidiaries (other than intercompany
Indebtedness); provided that:

                (1)     the principal amount (or initial accreted value, if
                        applicable) of such Permitted Refinancing Indebtedness
                        does not exceed the principal amount (or accreted value,
                        if applicable) of the Indebtedness extended, refinanced,
                        renewed, replaced, defeased or refunded (plus all
                        accrued interest on the Indebtedness and the amount of
                        all expenses and premiums incurred in connection
                        therewith);

                (2)     such Permitted Refinancing Indebtedness has a final
                        maturity date not earlier than the final maturity date
                        of, and has a Weighted Average Life to Maturity equal to
                        or greater than the Weighted Average Life to Maturity
                        of, the Indebtedness being extended, refinanced,
                        renewed, replaced, defeased or refunded; and

                (3)     if the Indebtedness being extended, refinanced, renewed,
                        replaced, defeased or refunded is subordinated in right
                        of payment to the Notes, such Permitted Refinancing
                        Indebtedness is subordinated in right of payment to the
                        Notes on terms at least as favorable to the Holders of
                        Notes as those contained in the documentation governing
                        the Indebtedness being extended, refinanced, renewed,
                        replaced, defeased or refunded.

        "Person" means any individual, corporation, partnership, joint venture,
association, joint-stock company, trust, unincorporated organization, limited
liability company or government or other entity.

                                       21

<PAGE>

        "Predecessor Note" of any particular Note means every previous Note
issued before, and evidencing all or a portion of the same Indebtedness as that
evidenced by, such particular Note; and, for the purposes of this definition,
any Note authenticated and delivered under Section 2.07 in exchange for or in
lieu of a mutilated, destroyed, lost or stolen Note shall be deemed to evidence
the same Indebtedness as the mutilated, destroyed, lost or stolen Note.

        "Principal" means Steven B. Dodge and any Related Party of Steven B.
Dodge.

        "Public Equity Offering" means any underwritten public offering of
common stock of the Company pursuant to an effective registration statement
under the Securities Act.

        "Purchase Agreement" means the Purchase Agreement, dated as of January
22, 2003, among the Company, the Parent, the Guarantors (from and after the
consummation of the Escrow Corp. Merger) and the Purchasers, as such agreement
may be amended from time to time.

        "Purchasers" means Credit Suisse First Boston LLC and Goldman, Sachs &
Co.

        "Qualified Proceeds" means assets that are used or useful in, or Capital
Stock of any Person engaged in, a Permitted Business.

        "Rating Agencies" mean Moody's and S&P.

        "Registered Notes" means the Exchange Notes and all other Notes sold or
otherwise disposed of pursuant to an effective registration statement under the
Securities Act, together with their respective Successor Notes.

        "Registration Default" has the meaning set forth in the form of Note
attached as Exhibit A.

        "Registration Rights Agreement" means the Registration Rights Agreement
among American Towers, Inc., the Guarantors (from and after the consummation of
the Escrow Corp. Merger) and the Purchasers, dated as of the Issue Date, as such
agreement may be amended, modified or supplemented from time to time.

        "Regulation S" means Regulation S under the Securities Act (or any
successor provision), as it may be amended from time to time.

        "Regulation S Certificate" means a certificate substantially in the form
set forth in Exhibit D.

        "Regulation S Global Note" has the meaning specified in Section 2.01(d).

        "Regulation S Legend" means a legend substantially in the form of the
legend required in the form of Note attached as Exhibit A to be placed upon each
Regulation S Note.

        "Regulation S Notes" means all Notes required pursuant to Section
2.06(f)(ii) to bear a Regulation S Legend. Such term includes the Regulation S
Global Note.

                                       22

<PAGE>

        "Related Party" with respect to the Principal means:

                (1)     any Person that is a Subsidiary of the Principal; or

                (2)     any trust, corporation, partnership, limited liability
                        company or other entity, the beneficiaries,
                        stockholders, members, partners, owners or Persons
                        beneficially holding an over-50% controlling interest of
                        which consists of the Principal and/or such other
                        Persons referred to in the immediately preceding clause
                        (1).

        "Representative" means the indenture trustee or other trustee, agent or
representative for any Senior Debt.

        "Responsible Officer" with respect to the Trustee, means any officer
within the Corporate Trust Administration of the Trustee (or any successor group
of the Trustee) or any other officer of the Trustee customarily performing
functions similar to those performed by any of the above designated officers and
also means, with respect to a particular corporate trust matter, any other
officer to whom such matter is referred because of his knowledge of and
familiarity with the particular subject and who shall have direct responsibility
for the administration of its Indenture.

        "Restricted Definitive Note" means a Definitive Note bearing the Private
Placement Legend.

        "Restricted Global Note" has the meaning specified in Section 2.01(d).

        "Restricted Investment" means an Investment other than a Permitted
Investment.

        "Restricted Notes" means all Notes required pursuant to Section
2.06(f)(ii) to bear any Restricted Notes Legend. Such term includes the
Restricted Global Note.

        "Restricted Notes Certificate" means a certificate substantially in the
form set forth in Exhibit E.

        "Restricted Notes Legend" means, collectively, the legends substantially
in the forms of the legends required in the form of Note attached as Exhibit A
to be placed upon each Restricted Note.

        "Restricted Period" means the period of 41 consecutive days beginning on
and including the later of (i) the day on which Notes are first offered to
persons other than distributors (as defined in Regulation S) in reliance on
Regulation S and (ii) the Issue Date.

        "Restricted Subsidiary" of a Person means any Subsidiary of such Person
that is not an Unrestricted Subsidiary and, in the absence of any designation,
means a Restricted Subsidiary of the Company or of a Sister Guarantor, as the
case may be, and, for purposes of any financial calculations with respect to the
Parent, shall mean the Company, the Sister Guarantors and the Restricted
Subsidiaries of the Company and the Sister Guarantors.

                                       23

<PAGE>

        "Rule 144A" means Rule 144A under the Securities Act (or any successor
provision), as such Rule 144A may be amended from time to time.

        "Rule 144A Notes" means the Notes purchased by the Purchasers from the
Company pursuant to the Purchase Agreement.

        "S&P" means Standard & Poor's Ratings Service or any successor to the
rating agency business thereof.

        "SEC" means the Securities and Exchange Commission.

        "Securities Act" means the Securities Act of 1933, as amended.

        "Securities Act Legend" means a Restricted Notes Legend or a Regulation
S Legend.

        "Senior Debt" means:

                (1)     in the case of the Company or any Group Guarantor:

                        (a)     all Indebtedness of the Company or any Group
                                Guarantor outstanding under clause (1) of the
                                second paragraph of Section 4.09 hereof
                                (including, without limitation, the Credit
                                Agreement) and all Hedging Obligations with
                                respect thereto; and

                        (b)     all Obligations with respect to the items listed
                                in the preceding clause (a); and

                (2)     in the case of the Parent:

                        (a)     all Indebtedness of the Parent outstanding under
                                clause (1) of the second paragraph of Section
                                4.09 hereof (including, without limitation, the
                                Credit Agreement) and all Hedging Obligations
                                with respect thereto;

                        (b)     any other Indebtedness of the Parent, unless the
                                instrument under which such Indebtedness is
                                incurred expressly provides that it is on parity
                                with or subordinated in right of payment to the
                                Notes or any Note Guarantee; and

                        (c)     all Obligations with respect to the items listed
                                in the preceding clauses (a) and (b).

                Notwithstanding anything to the contrary in the preceding,
Senior Debt shall not include:

                (1)     any liability for federal, state, local or other taxes
                        owed or owing by the Company or any Guarantor;

                                               24

<PAGE>

                (2)     any intercompany Indebtedness of the Company, any Sister
                        Guarantor or any of their Subsidiaries to the Company,
                        any Sister Guarantor or any of their Affiliates;

                (3)     any trade payables; or

                (4)     the portion of any Indebtedness that is incurred in
                        violation of this Indenture.

        "Senior Note Indenture" means that certain indenture, dated January 31,
2001 with the Bank of New York as trustee, as amended or supplemented from time
to time, relating to the Senior Notes Due 2009.

        "Senior Notes Due 2009" means, collectively, those certain 9-3/8% Senior
Notes due 2009 of the Parent issued pursuant to the Senior Note Indenture.

        "Separation Date" means the earliest of:

                (1)     the date that is 180 days from the Issue Date;

                (2)     the commencement of the Exchange Offer;

                (3)     the effectiveness of any shelf registration statement
                        with respect to the Warrants;

                (4)     such date as Credit Suisse First Boston LLC in its sole
                        discretion shall determine; and

                (5)     in the event of a Change in Control, the date the
                        Company mails the requisite notice to the Holders.

        "Significant Subsidiary" means any Subsidiary that would be a
"significant subsidiary" as defined in Article 1, Rule 1-02 of Regulation S-X,
promulgated pursuant to the Securities Act, as such Regulation is in effect on
the date hereof.

        "Sister Guarantors" means American Tower International, Inc., American
Tower LLC and Towersites Monitoring, Inc.

        "Stated Maturity" means, with respect to any installment of interest or
principal on any series of Indebtedness, the date on which the payment of
interest or principal was scheduled to be paid in the original documentation
governing such Indebtedness, and shall not include any contingent obligations to
repay, redeem or repurchase any such interest or principal prior to the date
originally scheduled for the payment thereof.

        "Step-Down Date" has the meaning set forth in the form of Note attached
as Exhibit A.

        "Subsidiary" means, with respect to any specified Person:

                                       25

<PAGE>

                (1)     any corporation, association or other business entity of
                        which more than 50% of the total voting power of shares
                        of Capital Stock entitled (without regard to the
                        occurrence of any contingency) to vote in the election
                        of directors, managers or trustees of the corporation,
                        association or other business entity is at the time
                        owned or controlled, directly or indirectly, by that
                        Person or one or more of the other Subsidiaries of that
                        Person (or a combination thereof); and

                (2)     any partnership (a) the sole general partner or the
                        managing general partner of which is such Person or a
                        Subsidiary of such Person or (b) the only general
                        partners of which are that Person or one or more
                        Subsidiaries of that Person (or any combination
                        thereof).

        "Successor Note" of any particular Note means every Note issued after,
and evidencing all or a portion of the same debt as that evidenced by, such
particular Note; and, for purposes of this definition, any Note authenticated
and delivered under Section 2.07 in exchange for or in lieu of a mutilated,
destroyed, lost or stolen Note shall be deemed to evidence the same debt as the
mutilated, destroyed, lost or stolen Note.

        "Surplus Asset Sale" means (i) an Asset Sale of communications
transmission towers that were acquired from AT&T Corporation and its Affiliates,
have an aggregate book value on the Parent's GAAP balance sheet at September 30,
2002 and at the Issue Date of not more than $20.0 million, and are shown on the
GAAP accounting records of the Parent at September 30, 2002 and at the Issue
Date as being held for disposal, and (ii) Asset Sales in any one-year period for
aggregate net proceeds of up to $5.0 million.

        "Tax Sharing Agreement" means the Tax Sharing Agreement, dated as of
January 1, 2000, among the Company, the Parent and other Subsidiaries of the
Parent.

        "Teleports Business" means the business of providing domestic and
international satellite and internet protocol network transmission services.

        "TIA" means the Trust Indenture Act of 1939 (15 U.S.C. Sections
77aaa-77bbbb) as in effect on the date on which this Indenture is qualified
under the TIA.

        "Tower Asset Exchange" means any transaction in which the Company, a
Sister Guarantor or one or more of the Restricted Subsidiaries exchanges assets
for, or issues its Capital Stock in exchange for, Tower Assets and/or cash or
Cash Equivalents where the fair market value (evidenced by a resolution of the
Board of Directors of the Company set forth in an Officers' Certificate
delivered to the Trustee) of the Tower Assets and cash or Cash Equivalents
received by the Company, the Sister Guarantors and the Restricted Subsidiaries
in such exchange is at least equal to the fair market value of the assets
disposed of, or the Capital Stock issued, in such exchange.

        "Tower Assets" means wireless transmission or broadcast towers and
related assets that are located on the site of a wireless transmission or
broadcast tower.

                                       26

<PAGE>

        "Tower Cash Flow" means, with respect to any Person and for any period,
the Consolidated Cash Flow of such Person and its Restricted Subsidiaries, in
each case that is directly attributable (including related expenses) to (i) site
rental revenue or license fees (including space reservation payments) paid to
lease, sublease or retain space on communications sites owned or leased by such
Person or its Restricted Subsidiaries, (ii) fees paid to such Person or its
Restricted Subsidiaries for management of communications sites and (iii) real
estate lease and similar payments (whether or not related to communications
sites) paid to such Person or its Restricted Subsidiaries to the extent included
in the same operating segment for GAAP reporting purposes as site rental
revenue, all determined on a consolidated basis and in accordance with GAAP.
Tower Cash Flow shall not include revenue or expenses attributable to non-site
rental services provided by such Person or any of its Restricted Subsidiaries to
lessees of communication sites or revenues derived from the sale of assets.

        "Trustee" means the party named as such above until a successor replaces
it in accordance with the applicable provisions of this Indenture and thereafter
means the successor serving hereunder.

        "Unrestricted Notes Certificate" means a certificate substantially in
the form set forth in Exhibit F.

        "Unrestricted Subsidiary" means (a) upon the consummation of the Escrow
Corp. Merger, any of ATS-Needham LLC, Haysville Towers, LLC, ATC Realty Holding,
Inc., ATC Connecticut, Inc., ATC Westwood, Inc., ATC Presidential Way, Inc., 10
Presidential Way Associates, LLC, Unisite/OmniPoint FL Tower Venture, LLC,
Unisite/OmniPoint NE Tower Venture, LLC and Unisite/OmniPoint PA Tower Venture,
LLC or (b) any Subsidiary of the Company or any Sister Guarantor that is
designated by the Board of Directors of the Company, on or after the Issue Date,
as an Unrestricted Subsidiary pursuant to a board resolution, but only to the
extent that such Subsidiary:

                (1)     has no Indebtedness other than Non-Recourse Debt or
                        Indebtedness owed to the Company, any Sister Guarantor
                        or any of the Restricted Subsidiaries;

                (2)     is not party to any agreement, contract, arrangement or
                        understanding with the Company, any Sister Guarantor or
                        any Restricted Subsidiary unless the terms of any such
                        agreement, contract, arrangement or understanding are no
                        less favorable to the Company, such Sister Guarantor or
                        such Restricted Subsidiary than those that might be
                        obtained at the time from Persons who are not Affiliates
                        of the Company or the Sister Guarantors;

                (3)     is a Person with respect to which none of the Company, a
                        Sister Guarantor, or any of the Restricted Subsidiaries
                        has any direct or indirect obligation (a) to subscribe
                        for additional Equity Interests or (b) to maintain or
                        preserve such Person's financial condition or to cause
                        such Person to achieve any specified levels of operating
                        results; and

                                       27

<PAGE>

                (4)     has not guaranteed or otherwise directly or indirectly
                        provided credit support for any Indebtedness of the
                        Company, any Sister Guarantor or any of the Restricted
                        Subsidiaries.

        Any designation of a Subsidiary of the Company or a Sister Guarantor as
an Unrestricted Subsidiary shall be evidenced to the Trustee by filing with the
Trustee a certified copy of the board resolution giving effect to such
designation and an Officers' Certificate certifying that such designation
complied with the preceding conditions and was permitted by Section 4.07 hereof.
If, at any time, any Unrestricted Subsidiary would fail to meet the preceding
requirements as an Unrestricted Subsidiary, it shall thereafter cease to be an
Unrestricted Subsidiary for purposes of this Indenture and any Indebtedness of
such Subsidiary shall be deemed to be incurred by a Restricted Subsidiary as of
such date and, if such Indebtedness is not permitted to be incurred as of such
date under Section 4.09 hereof, the Company or the Sister Guarantor, as
applicable, shall be in default under such Section. The Board of Directors of
the Company or a Sister Guarantor may at any time designate any Unrestricted
Subsidiary to be a Restricted Subsidiary; provided that such designation shall
be deemed to be an incurrence of Indebtedness by a Restricted Subsidiary of the
Company or the Sister Guarantor, as applicable, of any outstanding Indebtedness
of such Unrestricted Subsidiary and such designation shall only be permitted if
(1) such Indebtedness is permitted under Section 4.09 hereof; and (2) no Default
or Event of Default would be in existence following such designation.

        "Verestar" means Verestar, Inc. (formerly ATC Teleports Inc.), a
Delaware corporation.

        "U.S. Person" means a U.S. person as defined in Rule 902(o) under the
Securities Act.

        "Voting Stock" of any Person as of any date means the Capital Stock of
such Person that is at the time entitled to vote in the election of the Board of
Directors of such Person.

        "Warrants" means 808,000 warrants to purchase 11,389,012 shares of Class
A common stock of American Tower Corporation, as contemplated by the Offering
Circular.

        "Weighted Average Life to Maturity" means, when applied to any
Indebtedness at any date, the number of years obtained by dividing:

                (1)     the sum of the products obtained by multiplying (a) the
                        amount of each then remaining installment, sinking fund,
                        serial maturity or other required payments of principal,
                        including payment at final maturity, in respect of the
                        Indebtedness, by (b) the number of years (calculated to
                        the nearest one-twelfth) that shall elapse between such
                        date and the making of such payment; by

                (2)     the then outstanding principal amount of such
                        Indebtedness.

        "Wholly Owned Domestic Restricted Subsidiary" means any Wholly Owned
Restricted Subsidiary of the specified person that (i) was formed under the laws
of the United States or any state of the United States or the District of
Columbia and (ii) in the case of a Wholly Owned

                                       28

<PAGE>

Domestic Restricted Subsidiary of the Company or of a Sister Guarantor,
guarantees Indebtedness under the Credit Agreement or is a co-borrower
thereunder.

        "Wholly Owned Restricted Subsidiary" of any specified Person means a
Restricted Subsidiary of such Person all of the outstanding Capital Stock or
other ownership interests of which (other than directors' qualifying shares)
shall at the time be owned by such Person or by one or more Wholly Owned
Restricted Subsidiaries of such Person or by such Person and one or more Wholly
Owned Restricted Subsidiaries of such Person. If all of the outstanding Capital
Stock or other ownership interests (other than directors' qualifying shares) of
a Restricted Subsidiary of the Company or a Sister Guarantor that are not owned
by the Company or such Sister Guarantor are owned by one or more of the Company
or a Sister Guarantor or a Wholly Owned Restricted Subsidiary of the Company or
a Sister Guarantor, such Restricted Subsidiary shall be deemed to be a Wholly
Owned Restricted Subsidiary of the Company or a Sister Guarantor, as determined
by the Company.

        Section 1.02.   Other Definitions.

                                                                     DEFINED IN
                TERM                                                 SECTION
                ----                                                 ----------

                "Affiliate Transaction"............................. 4.11
                "Asset Sale Offer".................................. 3.09
                "Authentication Order".............................. 2.02
                "Change of Control Offer"........................... 4.14
                "Change of Control Payment"......................... 4.14
                "Change of Control Payment Date".................... 4.14
                "Covenant Defeasance"............................... 8.03
                "DTC"............................................... 2.03
                "Event of Default".................................. 6.01
                "Excess Proceeds"................................... 4.10
                "incur"............................................. 4.09
                "Investment Company Act Legend" .................... 2.06
                "Legal Defeasance".................................. 8.02
                "Mandatory Redemption Payment Date" ................ 3.08
                "Mandatory Redemption Price" ....................... 3.08
                "Offer Amount"...................................... 3.09
                "Offer Period"...................................... 3.09
                "OID Legend" ....................................... 2.06
                "Original Notes".................................... 2.02
                "Paying Agent"...................................... 2.03
                "Payment Blockage Notice" .......................... 11.03
                "Payment Default"................................... 6.01
                "Permitted Debt".................................... 4.09
                "Private Placement Legend" ......................... Exhibit A
                "Purchase Date"..................................... 3.09

                                       29

<PAGE>

                                                                     DEFINED IN
                TERM                                                 SECTION
                ----                                                 ----------

                "Registrar"......................................... 2.03
                "Release Date" ..................................... 3.08
                "Restricted Payments"............................... 4.07
                "restricted security" .............................. 2.06
                "Suspended Covenants"............................... 4.17
                "Unit Legend" ...................................... 2.06

        Section 1.03.   Incorporation by Reference of Trust Indenture Act.

        Whenever this Indenture refers to a provision of the TIA, the provision
is incorporated by reference in and made a part of this Indenture.

        The following TIA terms used in this Indenture have the following
meanings:

        "indenture securities" means the Notes;
        "indenture security Holder" means a Holder of a Note;
        "indenture to be qualified" means this Indenture;
        "indenture trustee" or "institutional trustee" means the Trustee; and
        "obligor" on the Notes means the Company and any successor obligor upon
the Notes.

        All other terms used in this Indenture that are defined by the TIA,
defined by the TIA's reference to another statute or defined by SEC rule under
the TIA have the meanings so assigned to them.

        Section 1.04.   Rules of Construction.

        Unless the context otherwise requires:

        (a)     a term has the meaning assigned to it;

        (b)     an accounting term not otherwise defined has the meaning
assigned to it in accordance with GAAP;

        (c)     "or" is not exclusive;

        (d)     words in the singular include the plural, and in the plural
include the singular;

        (e)     provisions apply to successive events and transactions; and

        (f)     references to sections of or rules under the Securities Act
shall be deemed to include substitute, replacement or successor sections or
rules adopted by the SEC from time to time.

                                       30

<PAGE>

                                    ARTICLE 2

                                    THE NOTES

        Section 2.01.   Form and Dating.

        (a)     General. The Notes and the Trustee's certificate of
authentication shall be substantially in the form of Exhibit A hereto. The Notes
may have notations, legends or endorsements required by law, stock exchange rule
or usage. Each Note shall be dated the date of its authentication. The Notes
shall be in denominations of $1,000 and integral multiples thereof.

        The Notes may consist of Original Notes and/or Exchange Notes, which
shall rank pari passu in right of payment with each other and with all other
existing and future senior subordinated obligations of the Company. Unless the
context otherwise requires, Original Notes and Exchange Notes shall be
considered collectively to be a single class for all purposes of this Indenture,
including without limitation waivers, amendments, redemptions and Asset Sale
Offers.

        The terms and provisions contained in the Notes shall constitute, and
are hereby expressly made, a part of this Indenture and the Company and the
Trustee, by their execution and delivery of this Indenture, expressly agree to
such terms and provisions and to be bound thereby. However, to the extent any
provision of any Note conflicts with the express provisions of this Indenture,
the provisions of this Indenture shall govern and be controlling.

        (b)     Global Notes. Notes issued in global form shall be substantially
in the form of Exhibit A attached hereto (including the Global Note Legend
thereon and the "Schedule of Exchanges of Interests in the Global Note" attached
thereto). Notes issued in definitive form shall be substantially in the form of
Exhibit A attached hereto (but without the Global Note Legend thereon and
without the "Schedule of Exchanges of Interests in the Global Note" attached
thereto).

        Each Global Note shall represent such of the outstanding Notes as shall
be specified therein and each shall provide that it shall represent the
aggregate principal amount at maturity of outstanding Notes from time to time
endorsed thereon and that the aggregate principal amount at maturity of
outstanding Notes represented thereby may from time to time be reduced or
increased, as appropriate, to reflect exchanges, redemptions, repurchases and
transfers of interests. Any endorsement of a Global Note to reflect the amount
of any increase or decrease in the aggregate principal amount at maturity of
outstanding Notes represented thereby shall be made by the Trustee or the
Custodian, at the direction of the Trustee, in accordance with instructions
given by the Holder thereof as required by Section 2.06 hereof.

        (c)     Euroclear and Clearstream Procedures Applicable. The provisions
of the "Operating Procedures of the Euroclear System" and "Terms and Conditions
Governing Use of Euroclear" and the "General Terms and Conditions of
Clearstream" and "Customer Handbook" of Clearstream shall be applicable to
transfers of beneficial interests in Global Notes that are held by Participants
through Euroclear or Clearstream.

                                       31

<PAGE>

        (d)     Restricted and Regulation S Global Notes. Upon their original
issuance, Rule 144A Notes shall be issued in the form of one or more Global
Notes registered in the name of the Depositary or its nominee and deposited with
the Trustee, as Custodian for the Depositary, for credit by the Depositary to
the respective accounts of beneficial owners of the Notes represented thereby
(or such other accounts as they may direct). Such Global Notes, together with
their Successor Notes which are Global Notes other than the Regulation S Global
Notes, are collectively herein called the "Restricted Global Note".

        Upon their original issuance, Regulation S Notes shall be issued in the
form of one or more Global Notes registered in the name of the Depositary, or
its nominee and deposited with the Trustee, as Custodian for the Depositary, for
credit to the respective accounts of the beneficial owners of the Notes
represented thereby (or such other accounts as they may direct), provided that
upon such deposit all such Notes shall be credited to or through accounts
maintained at the Depositary by or on behalf of Euroclear or Clearsteam. Such
Global Notes, together with their Successor Notes which are Global Notes other
than the Restricted Global Note, are collectively herein called the "Regulation
S Global Note".

        Section 2.02.   Execution and Authentication.

        Two Officers shall sign the Notes for the Company by manual or facsimile
signature.

        If an Officer whose signature is on a Note no longer holds that office
at the time a Note is authenticated, the Note shall nevertheless be valid.

        A Note shall not be valid until authenticated by the manual signature of
the Trustee. The signature shall be conclusive evidence that the Note has been
authenticated under this Indenture.

        The Trustee shall, upon a written order of the Company signed by two
Officers (an "Authentication Order"), authenticate Notes for original issue on
the Issue Date in an aggregate principal amount at maturity not to exceed $808
million (the "Original Notes"). The aggregate principal amount at maturity of
Notes (including Exchange Notes) outstanding at any time may not exceed the
aggregate principal amount at maturity stated in paragraph 4 of the Notes except
as provided in Section 2.08 hereof. Notes shall be dated the date of their
authentication.

        At any time and from time to time after the execution and delivery of
this Indenture and after the effectiveness of a Registration Statement under the
Securities Act with respect thereto, the Company may deliver Exchange Notes
executed by the Company to the Trustee for authentication, together with a
Company Order for the authentication and delivery of such Exchange Notes and a
like principal amount at maturity of Original Notes for cancellation in
accordance with Section 2.11 of this Indenture, and the Trustee in accordance
with the Company Order shall authenticate and deliver such Notes. In
authenticating such Exchange Notes, and accepting the additional
responsibilities under this Indenture in relation to such Notes, the Trustee
shall be entitled to receive, and (subject to Section 7.01) shall be fully
protected in relying upon, an Opinion of Counsel stating,

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                (i)     that such Exchange Notes have been duly and validly
                        issued in accordance with the terms of this Indenture,
                        and are entitled to all the rights and benefits set
                        forth herein; and

                (ii)    that the issuance of the Exchange Notes in exchange for
                        the Original Notes has been effected in compliance with
                        the Securities Act.

        The Trustee may appoint an authenticating agent acceptable to the
Company to authenticate Notes. An authenticating agent may authenticate Notes
whenever the Trustee may do so. Each reference in this Indenture to
authentication by the Trustee includes authentication by such agent. An
authenticating agent has the same rights as an Agent to deal with Holders or an
Affiliate of the Company.

        Section 2.03.   Registrar and Paying Agent.

        The Company shall maintain an office or agency where Notes may be
presented for registration of transfer or for exchange ("Registrar") and an
office or agency where Notes may be presented for payment ("Paying Agent"). The
Registrar shall keep a register of the Notes and of their transfer and exchange.
The Company may appoint one or more co-registrars and one or more additional
paying agents. The term "Registrar" includes any co-registrar and the term
"Paying Agent" includes any additional paying agent. The Company may change any
Paying Agent or Registrar without notice to any Holder. The Company shall
promptly notify the Trustee in writing of the name and address of any Agent not
a party to this Indenture. If the Company fails to appoint or maintain another
entity as Registrar or Paying Agent, the Trustee shall act as such. The Company
or any of its Subsidiaries may act as Paying Agent or Registrar.

        The Company initially appoints The Depository Trust Company ("DTC") to
act as Depositary with respect to the Global Notes.

        The Company initially appoints the Trustee to act as the Registrar and
Paying Agent and to act as Custodian with respect to the Global Notes.

        Section 2.04.   Paying Agent to Hold Money in Trust.

        The Company shall require each Paying Agent other than the Trustee to
agree in writing that the Paying Agent shall hold in trust for the benefit of
the Holders or the Trustee all money held by the Paying Agent for the payment of
Accreted Value of, or premium, if any, on the Notes, and shall notify the
Trustee of any default by the Company in making any such payment. While any such
default continues, the Trustee may require a Paying Agent to pay all money held
by it to the Trustee. The Company at any time may require a Paying Agent to pay
all money held by it to the Trustee. Upon payment over to the Trustee, the
Paying Agent (if other than the Company or a Subsidiary) shall have no further
liability for the money. If the Company or a Subsidiary acts as Paying Agent, it
shall segregate and hold in a separate trust fund for the benefit of the Holders
all money held by it as Paying Agent. Upon any bankruptcy or reorganization
proceedings relating to the Company, the Trustee shall serve as Paying Agent for
the Notes.

                                       33

<PAGE>

        Section 2.05.   Holder Lists.

        The Trustee shall preserve in as current a form as is reasonably
practicable the most recent list available to it of the names and addresses of
all Holders and shall otherwise comply with TIA Section 312(a). If the Trustee
is not the Registrar, the Company shall furnish to the Trustee at least seven
Business Days before February 1 and August 1 of any given year and at such other
times as the Trustee may request in writing, a list in such form and as of such
date as the Trustee may reasonably require of the names and addresses of the
Holders of Notes, and the Company shall otherwise comply with TIA Section
312(a).

        Section 2.06.   Transfer and Exchange.

        (a)     Transfer and Exchange of Global Notes. A Global Note may not be
transferred as a whole except by the Depositary to a nominee of the Depositary,
by a nominee of the Depositary to the Depositary or to another nominee of the
Depositary, or by the Depositary or any such nominee to a successor Depositary
or a nominee of such successor Depositary. All Global Notes shall be exchanged
by the Company for Definitive Notes if (i) the Company delivers to the Trustee
notice from the Depositary that it is unwilling or unable to continue to act as
Depositary or that it is no longer a clearing agency registered under the
Exchange Act and, in either case, a successor Depositary is not appointed by the
Company within 120 days after the date of such notice from the Depositary, (ii)
the Company in its sole discretion determines that the Global Notes (in whole
but not in part) should be exchanged for Definitive Notes and delivers a written
notice to such effect to the Trustee, or (iii) upon request of a Holder if there
shall have occurred and be continuing a Default or an Event of Default. Upon the
occurrence of any of the preceding events in (i), (ii) or (iii) above,
Definitive Notes shall be issued in such names as the Depositary shall instruct
the Trustee. Global Notes also may be exchanged or replaced, in whole or in
part, as provided in Sections 2.07 and 2.10 hereof. Every Note authenticated and
delivered in exchange for, or in lieu of, a Global Note or any portion thereof,
pursuant to this Section 2.06, or Section 2.07 or 2.10 hereof, shall be
authenticated and delivered in the form of, and shall be, a Global Note. A
Global Note may not be exchanged for another Note other than as provided in this
Section 2.06(a); however, beneficial interests in a Global Note may be
transferred and exchanged as provided in Section 2.06(b), (c) or (f) hereof.

        (b)     Transfer and Exchange of Beneficial Interests in the Global
Notes. The transfer and exchange of beneficial interests in the Global Notes
shall be effected through the Depositary, in accordance with the provisions of
this Indenture and the Applicable Procedures. Transfers of beneficial interests
in the Global Notes also shall require compliance with either subparagraph (i)
or (ii) below, as applicable, as well as one or more of the other following
subparagraphs, as applicable:

                (i)     Transfer of Beneficial Interests in the Same Global
                        Note. Beneficial interests in any Global Note may be
                        transferred to Persons who take delivery thereof in the
                        form of a beneficial interest in the same Global Note.
                        No written orders or instructions shall be required to
                        be delivered to the Registrar to effect the transfers
                        described in this Section 2.06(b)(i).

                                       34

<PAGE>

                (ii)    All Other Transfers and Exchanges of Beneficial
                        Interests in Global Notes. In connection with all
                        transfers and exchanges of beneficial interests that are
                        not subject to Section 2.06(b)(i) above, the transferor
                        of such beneficial interest must deliver to the
                        Registrar either (A) (1) a written order from a
                        Participant or an Indirect Participant given to the
                        Depositary in accordance with the Applicable Procedures
                        directing the Depositary to credit or cause to be
                        credited a beneficial interest in another Global Note in
                        an amount equal to the beneficial interest to be
                        transferred or exchanged and (2) instructions given in
                        accordance with the Applicable Procedures containing
                        information regarding the Participant account to be
                        credited with such increase or (B) (1) a written order
                        from a Participant or an Indirect Participant given to
                        the Depositary in accordance with the Applicable
                        Procedures directing the Depositary to cause to be
                        issued a Definitive Note in an amount equal to the
                        beneficial interest to be transferred or exchanged and
                        (2) instructions given by the Depositary to the
                        Registrar containing information regarding the Person in
                        whose name such Definitive Note shall be registered to
                        effect the transfer or exchange referred to in (1)
                        above. Upon satisfaction of all of the requirements for
                        transfer or exchange of beneficial interests in Global
                        Notes contained in this Indenture and the Notes or
                        otherwise applicable under the Securities Act, the
                        Trustee shall adjust the principal amount at maturity of
                        the relevant Global Note(s) pursuant to Section 2.06(g)
                        hereof.

                (iii)   Restricted Global Note to Regulation S Global Note. If
                        the owner of a beneficial interest in the Restricted
                        Global Note wishes at any time to transfer such interest
                        to a Person who wishes to acquire the same in the form
                        of a beneficial interest in the Regulation S Global
                        Note, such transfer may be effected only in accordance
                        with the provisions of this clause (iii) and clause (v)
                        below and subject to the Applicable Procedures. Upon
                        receipt by the Trustee, as Registrar, of (A) an order
                        given by the Depositary or its authorized representative
                        directing that a beneficial interest in the Regulation S
                        Global Note in a specified principal amount at maturity
                        be credited to a specified Participant's account and
                        that a beneficial interest in the Restricted Global Note
                        in an equal principal amount at maturity be debited from
                        another specified Participant's account and (B) a
                        Regulation S Certificate, satisfactory to the Trustee
                        and duly executed by the owner of such beneficial
                        interest in the Restricted Global Note or his attorney
                        duly authorized in writing, then the Trustee, as
                        Registrar but subject to clause (v) below, shall reduce
                        the principal amount at maturity of the Restricted
                        Global Note and increase the principal amount at
                        maturity of the Regulation S Global Note by such
                        specified principal amount at maturity.

                (iv)    Regulation S Global Note to Restricted Global Note. If
                        the owner of a beneficial interest in the Regulation S
                        Global Note wishes at any time to

                                       35

<PAGE>

                        transfer such interest to a Person who wishes to acquire
                        the same in the form of a beneficial interest in the
                        Restricted Global Note, such transfer may be effected
                        only in accordance with this clause (iv) and subject to
                        the Applicable Procedures. Upon receipt by the Trustee,
                        as Registrar, of (A) an order given by the Depositary or
                        its authorized representative directing that a
                        beneficial interest in the Restricted Global Note in a
                        specified principal amount at maturity be credited to a
                        specified Participant's account and that a beneficial
                        interest in the Regulation S Global Note in an equal
                        principal amount at maturity be debited from another
                        specified Participant's account and (B) if such transfer
                        is to occur during the Restricted Period, a Restricted
                        Notes Certificate, satisfactory to the Trustee and duly
                        executed by the owner of such beneficial interest in the
                        Regulation S Global Note or his attorney duly authorized
                        in writing, then the Trustee, as Registrar, shall reduce
                        the principal amount at maturity of the Regulation S
                        Global Note and increase the principal amount at
                        maturity of the Restricted Global Note by such specified
                        principal amount at maturity.

                (v)     Regulation S Global Note to be Held Through Euroclear or
                        Clearsteam during Restricted Period. The Company shall
                        use its best efforts to cause the Depositary to ensure
                        that, until the expiration of the Restricted Period,
                        beneficial interests in the Regulation S Global Note may
                        be held only in or through accounts maintained at the
                        Depositary by Euroclear or Clearsteam (or by
                        Participants acting for the account thereof), and no
                        person shall be entitled to effect any transfer or
                        exchange that would result in any such interest being
                        held otherwise than in or through such an account;
                        provided that this clause (v) shall not prohibit any
                        transfer or exchange of such an interest in accordance
                        with clause (iv) above.

        (c)     Transfer or Exchange of Beneficial Interests for Definitive
Notes. If any Holder of a beneficial interest in a Global Note proposes to
exchange such beneficial interest for a Definitive Note or to transfer such
beneficial interest to a Person who takes delivery thereof in the form of a
Definitive Note, then, upon satisfaction of the conditions set forth in Sections
2.06(a) and 2.06(b)(ii) hereof, the Trustee shall cause the aggregate principal
amount at maturity of the applicable Global Note to be reduced accordingly
pursuant to Section 2.06(g) hereof, and the Company shall execute and the
Trustee shall authenticate and deliver to the Person designated in the
instructions a Definitive Note in the appropriate principal amount at maturity.
Any Definitive Note issued in exchange for a beneficial interest pursuant to
this Section 2.06(c) shall bear the legend restricting transfers that is borne
by such Global Note and shall be registered in such name or names and in such
authorized denomination or denominations as the holder of such beneficial
interest shall instruct the Registrar through instructions from the Depositary
and the Participant or Indirect Participant.

        (d)     Transfer or Exchange of Definitive Notes for Beneficial
Interests. Upon request by a Holder of Definitive Notes to exchange such
Definitive Notes for a beneficial interest in a

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<PAGE>

Global Note and such requesting Holder's presenting or surrendering to the
Registrar the Definitive Notes duly endorsed or accompanied by a written
instruction of transfer in form satisfactory to the Registrar duly executed by
such Holder or by its attorney, duly authorized in writing, the Registrar shall
register the transfer or exchange of Definitive Notes and effect the transfer or
exchange through the Depositary, in accordance with the provisions of this
Indenture and the Applicable Procedures. The Trustee shall cancel the Definitive
Note and cause the aggregate principal amount at maturity of the applicable
Global Note to be increased accordingly pursuant to the terms of this Indenture
and the Applicable Procedures. If the Definitive Note to be transferred in whole
or in part is a Restricted Note, or is a Regulation S Note and the transfer is
to occur during the Restricted Period, then the Trustee shall have received (A)
a Restricted Notes Certificate, satisfactory to the Trustee and duly executed by
the transferor Holder or his attorney duly authorized in writing, in which case
the transferee Holder shall take delivery in the form of a beneficial interest
in the Restricted Global Note, or (B) a Regulation S Certificate, satisfactory
to the Trustee and duly executed by the transferor Holder or his attorney duly
authorized in writing, in which case the transferee Holder shall take delivery
in the form of a beneficial interest in the Regulation S Global Note (subject in
every case to Section 2.06(f)).

        (e)     Transfer and Exchange of Definitive Notes for Definitive Notes.
Upon request by a Holder of Definitive Notes and such requesting Holder's
presenting or surrendering to the Registrar the Definitive Notes duly endorsed
or accompanied by a written instruction of transfer in form satisfactory to the
Registrar duly executed by such Holder or by its attorney, duly authorized in
writing, the Registrar shall register the transfer or exchange of Definitive
Notes; provided that, if the Note to be transferred in whole or in part is a
Restricted Note, or is a Regulation S Note and the transfer is to occur during
the Restricted Period, then the Trustee shall have received (A) a Restricted
Notes Certificate, satisfactory to the Trustee and duly executed by the
transferor Holder or his attorney duly authorized in writing, in which case the
transferee Holder shall take delivery in the form of a Restricted Note, or (B) a
Regulation S Certificate, satisfactory to the Trustee and duly executed by the
transferor Holder or his attorney duly authorized in writing, in which case the
transferee Holder shall take delivery in the form of a Regulation S Note
(subject in every case to Section 2.06(f)).

        (f)     Legends.

                (i)     Global Notes Legends. Each Global Note shall bear a
                        legend in substantially the following form:

        "THIS GLOBAL NOTE IS HELD BY THE DEPOSITARY (AS DEFINED IN THE INDENTURE
GOVERNING THIS NOTE) OR ITS NOMINEE IN CUSTODY FOR THE BENEFIT OF THE BENEFICIAL
OWNERS HEREOF, AND IS NOT TRANSFERABLE TO ANY PERSON UNDER ANY CIRCUMSTANCES
EXCEPT THAT (I) THE TRUSTEE MAY MAKE SUCH NOTATIONS HEREON AS MAY BE REQUIRED
PURSUANT TO SECTION 2.06 OF THE INDENTURE, (II) THIS GLOBAL NOTE MAY BE
EXCHANGED IN WHOLE BUT NOT IN PART PURSUANT TO SECTION 2.06(a) OF THE INDENTURE,
(III) THIS GLOBAL NOTE MAY BE DELIVERED TO THE TRUSTEE FOR CANCELLATION PURSUANT
TO SECTION 2.11 OF THE INDENTURE AND (IV) THIS GLOBAL NOTE

                                       37

<PAGE>

MAY BE TRANSFERRED TO A SUCCESSOR DEPOSITARY WITH THE PRIOR WRITTEN CONSENT OF
AMERICAN TOWER ESCROW CORPORATION."

                (ii)    Securities Act Legends. Rule 144A Notes and their
                        Successor Notes shall bear a Restricted Notes Legend,
                        and the Regulation S Notes and their Successor Notes
                        shall bear a Regulation S Legend, subject to the
                        following:

                        (1)     subject to the following sub-clauses of this
                                clause (ii), a Note or any portion thereof which
                                is exchanged, upon transfer or otherwise, for a
                                Global Note or any portion thereof shall bear
                                the Securities Act Legend borne by such Global
                                Note while represented thereby;

                        (2)     subject to the following sub-clauses of this
                                clause (ii), a new Note which is not a Global
                                Note and is issued in exchange for another Note
                                (including a Global Note) or any portion
                                thereof, upon transfer or otherwise, shall bear
                                the Securities Act Legend borne by such other
                                Note, provided that, if such new Note is
                                required pursuant to Section 2.06(a) to be
                                issued in the form of a Restricted Note, it
                                shall bear a Restricted Note Legend and, if such
                                new Note is so required to be issued in the form
                                of a Regulation S Note, it shall bear a
                                Regulation S Legend;

                        (3)     Registered Notes shall not bear a Securities Act
                                Legend;

                        (4)     at any time after the Notes may be freely
                                transferred without registration under the
                                Securities Act or without being subject to
                                transfer restrictions pursuant to the Securities
                                Act, a new Note which does not bear a Securities
                                Act Legend may be issued in exchange for or in
                                lieu of a Note (other than a Global Note) or any
                                portion thereof which bears such a legend if the
                                Trustee has received an Unrestricted Notes
                                Certificate, satisfactory to the Trustee and
                                duly executed by the Holder of such legended
                                Note or his attorney duly authorized in writing,
                                and after such date and receipt of such
                                certificate, the Trustee shall authenticate and
                                deliver such a new Note in exchange for or in
                                lieu of such other Note as provided in this
                                Article 2;

                        (5)     a new Note which does not bear a Securities Act
                                Legend may be issued in exchange for or in lieu
                                of a Note (other than a Global Note) or any
                                portion thereof which bears such a legend if, in
                                the Company's judgment, placing such a legend
                                upon such new Note is not necessary to ensure
                                compliance with the registration requirements of
                                the Securities Act, and the Trustee, at the
                                written

                                       38

<PAGE>

                                direction of the Company, shall authenticate and
                                deliver such new Note as provided in this
                                Article 2; and

                        (6)     notwithstanding the foregoing provisions of this
                                clause (ii) of Section 2.06(f), a Successor Note
                                of a Note that does not bear a particular form
                                of Securities Act Legend shall not bear such
                                form of legend unless the Company has reasonable
                                cause to believe that such Successor Note is a
                                "restricted security" within the meaning of Rule
                                144, in which case the Trustee, at the direction
                                of the Company, shall authenticate and deliver a
                                new Note bearing a Restricted Notes Legend in
                                exchange for such Successor Note as provided in
                                this Article 2.

                (iii)   Investment Company Act Legend. Prior to the Escrow Corp.
                        Merger, the Notes shall bear a legend in substantially
                        the following form (the "Investment Company Act
                        Legend"):

        "THE HOLDER OF THIS NOTE REPRESENTS THAT IT IS A "QUALIFIED PURCHASER"
AS DEFINED IN SECTION 2(A)(51) OF THE INVESTMENT COMPANY ACT AND THE RULES
THEREUNDER. THE FOLLOWING PERSONS ARE "QUALIFIED PURCHASERS": (I) ANY NATURAL
PERSON (ALONE OR JOINTLY WITH THAT PERSON'S SPOUSE) WHO OWNS NOT LESS THAN $5
MILLION IN "INVESTMENT" AS DEFINED IN RULE 2A51-L UNDER THE INVESTMENT COMPANY
ACT; (II) ANY COMPANY THAT OWNS NOT LESS THAN $5 MILLION IN INVESTMENTS AND THAT
IS OWNED DIRECTLY OR INDIRECTLY BY TWO OR MORE NATURAL PERSONS WHO ARE RELATED
AS SIBLINGS, SPOUSES (INCLUDING FORMER SPOUSES), OR DIRECT LINEAL DESCENDANTS
(WHETHER BY BIRTH OR ADOPTION), SPOUSES OF SUCH PERSONS, ESTATES OF SUCH
PERSONS, OR FOUNDATIONS, CHARITABLE ORGANIZATIONS, OR TRUSTS ESTABLISHED BY OR
FOR THE BENEFIT OF SUCH PERSONS, PROVIDED SUCH COMPANY WAS NOT FORMED FOR THE
PURPOSE OF ACQUIRING ESCROW CORP.'S SECURITIES; (III) ANY TRUST NOT COVERED BY
CLAUSE (II) THAT WAS NOT FORMED FOR THE PURPOSE OF ACQUIRING ESCROW CORP.'S
SECURITIES, AS TO WHICH THE TRUSTEE OR OTHER PERSON AUTHORIZED TO MAKE THE
TRUST'S INVESTMENT DECISIONS, AND EACH SETTLOR OR OTHER PERSON WHO HAS
CONTRIBUTED ASSETS TO THE TRUST, IS A PERSON DESCRIBED IN CLAUSES (I), (II) OR
(IV); (IV) ANY PERSON, ACTING FOR ITS OWN ACCOUNT OR THE ACCOUNTS OF OTHER
QUALIFIED PURCHASERS, WHO IN THE AGGREGATE OWNS AND INVESTS ON A DISCRETIONARY
BASIS NOT LESS THAN $25 MILLION IN INVESTMENTS; (V) ANY COMPANY, EACH OF THE
BENEFICIAL OWNERS OF WHICH IS A QUALIFIED PURCHASER, AND (VI) ANY PERSON THAT IS
A "QUALIFIED INSTITUTIONAL BUYER" AS DEFINED IN RULE 144A, EXCEPT THAT (A) A
DEALER IS A QUALIFIED PURCHASER ONLY IF IT OWNS AND INVESTS ON A DISCRETIONARY
BASIS NOT LESS THAN $25 MILLION IN SECURITIES OF COMPANIES THAT ARE NOT
AFFILIATED PERSONS OF THE DEALER; AND (B) ANY EMPLOYEE BENEFIT PLAN, OR TRUST
FUND HOLDING THE

                                       39

<PAGE>

ASSETS OF SUCH A PLAN, THAT IS A QUALIFIED INSTITUTIONAL BUYER IS A QUALIFIED
PURCHASER ONLY WITH RESPECT TO INVESTMENT DECISIONS MADE BY THE PLAN'S FIDUCIARY
TRUSTEE, OR SPONSOR OR, WITH RESPECT TO INVESTMENT DECISIONS MADE BY PLAN
BENEFICIARIES, SUCH BENEFICIARIES WHO ARE THEMSELVES QUALIFIED PURCHASERS."

                (iv)    Original Issue Discount Legend. Each Note shall bear a
                        legend in substantially the following form (the "OID
                        Legend"):

        "THIS SECURITY WAS ISSUED WITH ORIGINAL ISSUE DISCOUNT UNDER SECTION
1272, 1273 AND 1275 OF THE INTERNAL REVENUE CODE OF 1986, AS AMENDED. YOU MAY
CONTACT THE CHIEF FINANCIAL OFFICER OF THE COMPANY AT 116 HUNTINGTON AVENUE,
BOSTON, MA 02116, (617) 375-7500, WHO WILL PROVIDE YOU WITH ANY REQUIRED
INFORMATION REGARDING THE ORIGINAL ISSUE DISCOUNT."

                (v)     Unit Legend. Each Note issued prior to the Separation
                        Date shall bear a legend in substantially the following
                        form (the "Unit Legend"):

        "THE NOTES EVIDENCED BY THIS CERTIFICATE ARE INITIALLY ISSUED AS PART OF
AN ISSUANCE OF UNITS (THE "UNITS"), EACH OF WHICH CONSISTS OF $1,000 PRINCIPAL
AMOUNT AT MATURITY OF THE 12.25% SENIOR SUBORDINATED DISCOUNT NOTES DUE 2008
(THE "NOTES") OF ESCROW CORP. AND ONE WARRANT TO PURCHASE 14.0953 SHARES, PAR
VALUE $0.01 PER SHARE, OF AMERICAN TOWER CORPORATION.

        PRIOR TO THE EARLIEST TO OCCUR OF (I) 180 DAYS AFTER THE CLOSING OF THE
OFFERING, (II) THE DATE ON WHICH A REGISTRATION STATEMENT FOR A REGISTERED
EXCHANGE OFFER WITH RESPECT TO THE NOTES IS DECLARED EFFECTIVE UNDER THE
SECURITIES ACT, (III) THE DATE A SHELF REGISTRATION STATEMENT WITH RESPECT TO
THE WARRANTS IS DECLARED EFFECTIVE UNDER THE SECURITIES ACT, (IV) SUCH DATE AS
CREDIT SUISSE FIRST BOSTON LLC IN ITS SOLE DISCRETION SHALL DETERMINE AND (V) IN
THE EVENT OF A CHANGE OF CONTROL, THE DATE AMERICAN TOWER ESCROW CORPORATION (OR
ITS SUCCESSOR) MAILS THE REQUISITE NOTICE TO THE HOLDERS, THE NOTES EVIDENCED BY
THIS CERTIFICATE MAY NOT BE TRANSFERRED OR EXCHANGED SEPARATELY FROM, BUT MAY BE
TRANSFERRED OR EXCHANGED ONLY TOGETHER WITH, THE WARRANTS."

        (g)     Cancellation and/or Adjustment of Global Notes. At such time as
all beneficial interests in a particular Global Note have been exchanged for
Definitive Notes or a particular Global Note has been redeemed, repurchased or
canceled in whole and not in part, each such Global Note shall be returned to or
retained and canceled by the Trustee in accordance with Section 2.11 hereof. At
any time prior to such cancellation, if any beneficial interest in a Global Note
is exchanged for or transferred to a Person who shall take delivery thereof in
the form of a beneficial interest in another Global Note or for Definitive
Notes, the principal amount at

                                       40

<PAGE>

maturity of Notes represented by such Global Note shall be reduced accordingly
and an endorsement shall be made on such Global Note by the Trustee or by the
Depositary at the direction of the Trustee to reflect such reduction; and if the
beneficial interest is being exchanged for or transferred to a Person who shall
take delivery thereof in the form of a beneficial interest in another Global
Note, such other Global Note shall be increased accordingly and an endorsement
shall be made on such Global Note by the Trustee or by the Depositary at the
direction of the Trustee to reflect such increase.

        (h)     General Provisions Relating to Transfers and Exchanges.

                (i)     To permit registrations of transfers and exchanges, the
                        Company shall execute and the Trustee shall authenticate
                        Global Notes and Definitive Notes upon the Company's
                        order or at the Registrar's request.

                (ii)    No service charge shall be made to a holder of a
                        beneficial interest in a Global Note or to a Holder of a
                        Definitive Note for any registration of transfer or
                        exchange, but the Company may require payment of a sum
                        sufficient to cover any transfer tax or similar
                        governmental charge payable in connection therewith
                        (other than any such transfer taxes or similar
                        governmental charge payable upon exchange or transfer
                        pursuant to Sections 2.10, 3.06, 3.09, 4.10, 4.14 and
                        9.05 hereof).

                (iii)   The Registrar shall not be required to register the
                        transfer of or exchange any Note selected for redemption
                        in whole or in part, except the unredeemed portion of
                        any Note being redeemed in part.

                (iv)    All Global Notes and Definitive Notes issued upon any
                        registration of transfer or exchange of Global Notes or
                        Definitive Notes shall be the valid obligations of the
                        Company, evidencing the same debt, and entitled to the
                        same benefits under this Indenture, as the Global Notes
                        or Definitive Notes surrendered upon such registration
                        of transfer or exchange.

                (v)     The Company shall not be required (A) to issue, to
                        register the transfer of or to exchange any Notes during
                        a period beginning at the opening of business 15 days
                        before the day of any selection of Notes for redemption
                        under Section 3.02 hereof and ending at the close of
                        business on the day of selection, (B) to register the
                        transfer of or to exchange any Note so selected for
                        redemption in whole or in part, except the unredeemed
                        portion of any Note being redeemed in part or (C) to
                        register the transfer of or to exchange a Note between a
                        record date and the next succeeding Interest Payment
                        Date.

                (vi)    Prior to due presentment for the registration of a
                        transfer of any Note, the Trustee, any Agent and the
                        Company may deem and treat the Person in whose name any
                        Note is registered as the absolute owner of such Note
                        for the purpose of receiving payment of Accreted Value
                        of, Liquidated

                                       41

<PAGE>

                        Damages and premium, if any, on such Notes and for all
                        other purposes, and none of the Trustee, any Agent or
                        the Company shall be affected by notice to the contrary.

                (vii)   The Trustee shall authenticate Global Notes and
                        Definitive Notes in accordance with the provisions of
                        Section 2.02 hereof.

                (viii)  All certifications, certificates and Opinions of Counsel
                        required to be submitted to the Registrar pursuant to
                        this Section 2.06 to effect a registration of transfer
                        or exchange may be submitted by facsimile.

        Section 2.07.   Replacement Notes.

        If any mutilated Note is surrendered to the Trustee or the Company and
the Trustee receives evidence to its satisfaction of the destruction, loss or
theft of any Note, the Company shall issue and the Trustee, upon receipt of an
Authentication Order, shall authenticate a replacement Note if the Trustee's
requirements are met. If required by the Trustee or the Company, an indemnity
bond must be supplied by the Holder that is sufficient in the judgment of the
Trustee and the Company to protect the Company, the Trustee, any Agent and any
authenticating agent from any loss that any of them may suffer if a Note is
replaced. The Company may charge for its expenses in replacing a Note.

        Every replacement Note is an additional obligation of the Company and
shall be entitled to all of the benefits of this Indenture equally and
proportionately with all other Notes duly issued hereunder.

        Section 2.08.   Outstanding Notes.

        The Notes outstanding at any time are all the Notes authenticated by the
Trustee except for those canceled by it, those delivered to it for cancellation,
those reductions in the interest in a Global Note effected by the Trustee in
accordance with the provisions hereof, and those described in this Section as
not outstanding. Except as set forth in Section 2.09 hereof, a Note does not
cease to be outstanding because the Company or an Affiliate of the Company holds
the Note; however, Notes held by the Company or a Subsidiary of the Company
shall not be deemed to be outstanding for purposes of Section 3.07(b) hereof.

        If a Note is replaced pursuant to Section 2.07 hereof, it ceases to be
outstanding unless the Trustee receives proof satisfactory to it that the
replaced Note is held by a bona fide purchaser.

        If the principal amount at maturity of any Note is considered paid under
Section 4.01 hereof, it ceases to be outstanding and its Accreted Value ceases
to increase.

        If the Paying Agent (other than the Company, a Subsidiary or an
Affiliate of any thereof) holds, on a redemption date or maturity date, money
sufficient to pay Notes payable on that date,

                                       42

<PAGE>

then on and after that date such Notes shall be deemed to be no longer
outstanding and its Accreted Value shall cease to increase.

        Section 2.09.   Treasury Notes.

        In determining whether the Holders of the required principal amount at
maturity of Notes have concurred in any direction, waiver or consent, Notes
owned by the Company, or by any Person directly or indirectly controlling or
controlled by or under direct or indirect common control with the Company, shall
be considered as though not outstanding, except that for the purposes of
determining whether the Trustee shall be protected in relying on any such
direction, waiver or consent, only Notes that the Trustee knows are so owned
shall be so disregarded.

        Section 2.10.   Temporary Notes.

        Until certificates representing Notes are ready for delivery, the
Company may prepare and the Trustee, upon receipt of an Authentication Order,
shall authenticate temporary Notes. Temporary Notes shall be substantially in
the form of certificated Notes but may have variations that the Company
considers appropriate for temporary Notes and as shall be reasonably acceptable
to the Trustee. Without unreasonable delay, the Company shall prepare and the
Trustee shall authenticate definitive Notes in exchange for temporary Notes.

        Holders of temporary Notes shall be entitled to all of the benefits of
this Indenture.

        Section 2.11.   Cancellation.

        The Company at any time may deliver Notes to the Trustee for
cancellation. The Registrar and Paying Agent shall forward to the Trustee any
Notes surrendered to them for registration of transfer, exchange or payment. The
Trustee and no one else shall cancel all Notes surrendered for registration of
transfer, exchange, payment, replacement or cancellation and shall dispose of
such cancelled Notes in its customary manner in accordance with prudent business
practices. The Company may not issue new Notes to replace Notes that it has paid
or that have been delivered to the Trustee for cancellation except as expressly
permitted pursuant to this Indenture.

        Section 2.12.   CUSIP Numbers.

        The Trustee shall use "CUSIP" numbers in notices of redemption as a
convenience to Holders if the Company uses "CUSIP" numbers in issuing the Notes;
provided that any such notice may state that no representation is made as to the
correctness of such numbers either as printed on the Notes or as contained in
any notice of a redemption and that reliance may be placed only on the other
identification numbers printed on the Notes, and any such redemption shall not
be affected by any defect in or omission of such numbers. The Company shall
promptly notify the Trustee of any change in the "CUSIP" numbers.

                                       43

<PAGE>

                                    ARTICLE 3

                            REDEMPTION AND PREPAYMENT

        Section 3.01.   Notices to Trustee.

        If the Company elects to redeem Notes pursuant to the optional
redemption provisions of Section 3.07 hereof, it shall furnish to the Trustee,
at least 30 days but not more than 60 days before a redemption date, an
Officers' Certificate setting forth (1) the redemption date, (2) the principal
amount at maturity of Notes to be redeemed and (3) the redemption price
(expressed as a percentage of the Accreted Value).

        Section 3.02.   Selection of Notes to Be Redeemed.

        If less than all of the Notes are to be redeemed or purchased in an
offer to purchase at any time, the Trustee shall select the Notes to be redeemed
as follows:

                        (1)     if the Notes are listed on any national
                                securities exchange, in compliance with the
                                requirements of the principal national
                                securities exchange, if any, on which the Notes
                                are listed; or

                        (2)     if the Notes are not listed on any national
                                securities exchange, on a pro rata basis.

        No Notes of $1,000 of principal amount at maturity or less shall be
redeemed in part. Except as provided in the preceding sentence, provisions of
this Indenture that apply to Notes called for redemption also apply to portions
of Notes called for redemption.

        Notes called for redemption become due on the date fixed for redemption.

        Section 3.03.   Notice of Redemption.

        Subject to the provisions of Section 3.09 hereof, at least 30 days but
not more than 60 days before a redemption date, the Company shall mail or cause
to be mailed, by first class mail, a notice of redemption to each Holder whose
Notes are to be redeemed at its registered address. Notices of redemption may
not be conditional.

        The notice shall identify the Notes to be redeemed and shall state:

                        (1)     the redemption date;

                        (2)     the redemption price;

                        (3)     if any Note is being redeemed in part, the
                                portion of the principal amount at maturity of
                                such Note to be redeemed and that, after the
                                redemption date upon surrender of such Note, a
                                new Note or Notes

                                       44

<PAGE>

                                in principal amount at maturity equal to the
                                unredeemed portion shall be issued upon
                                cancellation of the original Note;

                        (4)     the name and address of the Paying Agent;

                        (5)     that Notes called for redemption must be
                                surrendered to the Paying Agent to collect the
                                redemption price;

                        (6)     that the Accreted Value of the Notes or portions
                                of them called for redemption shall cease to
                                increase on and after the redemption date;

                        (7)     the paragraph of the Notes and/or Section of
                                this Indenture pursuant to which the Notes
                                called for redemption are being redeemed; and

                        (8)     that no representation is made as to the
                                correctness or accuracy of the CUSIP number, if
                                any, listed in such notice or printed on the
                                Notes.

        At the Company's request, the Trustee shall give the notice of
redemption in the Company's name and at its expense; provided, however, that the
Company shall have delivered to the Trustee, at least 45 days prior to the
redemption date, an Officers' Certificate requesting that the Trustee give such
notice and setting forth the information to be stated in such notice as provided
in the preceding paragraph.

        Section 3.04.   Effect of Notice of Redemption.

        Once notice of redemption is mailed in accordance with Section 3.03
hereof, Notes called for redemption become irrevocably due and payable on the
redemption date at the redemption price.

        Section 3.05.   Deposit of Redemption Price.

        One Business Day prior to the redemption date, the Company shall deposit
with the Trustee or with the Paying Agent money sufficient to pay the redemption
price of all Notes to be redeemed on that date plus Liquidated Damages, if any.
The Trustee or the Paying Agent shall promptly return to the Company any money
deposited with the Trustee or the Paying Agent by the Company in excess of the
amounts necessary to pay the redemption price of, and Liquidated Damages, if
any, on, all Notes to be redeemed.

        If the Company complies with the provisions of the preceding paragraph,
on and after the redemption date, the Accreted Value of the Notes or the
portions of the Notes called for redemption shall cease to increase.

                                       45

<PAGE>

        Section 3.06.   Notes Redeemed in Part.

        Upon surrender of a Note that is redeemed in part, the Company shall
issue and, upon the Company's written request, the Trustee shall authenticate
for the Holder at the expense of the Company a new Note equal in principal
amount at maturity to the unredeemed portion of the Note surrendered. If a
Global Note is so surrendered, such new Note shall also be a Global Note.

        Section 3.07.   Optional Redemption.

        (a)     On or after February 1, 2006, the Company may redeem all or a
part of the Notes upon not less than 30 nor more than 60 days' notice, at the
redemption prices (expressed as percentages of Accreted Value) set forth below
plus Liquidated Damages, if any, on the Notes redeemed, to the applicable
redemption date, if redeemed during the twelve-month period beginning on
February 1 of the years indicated below:

        YEAR                                                  PERCENTAGE
        ----                                                  ----------
        2006................................................  106.125%
        2007................................................  103.063%
        2008 and thereafter.................................  100.000%

        (b)     Any redemption pursuant to this Section 3.07 shall be made
pursuant to the provisions of Section 3.01 through 3.06 hereof.

        Section 3.08.   Mandatory Redemption.

        (a)      If the Escrow Corp. Merger has not occurred on or before the
60th day after the Issue Date or, or such earlier date as the Company in good
faith reasonably determines that the conditions to the Escrow Corp. Merger
cannot be met and notifies the Trustee thereof in writing (in each case, a
"Release Date"), the Company shall redeem all and not less than all of the Notes
issued under this Indenture at a redemption price equal to 101% of the Accreted
Value of such Notes as of the redemption date (the "Mandatory Redemption
Price").

        (b)     The Company shall make the payment by not later than 12:00 noon
(New York City time) on the second Business Day after the Release Date (the
"Mandatory Redemption Payment Date"). The payment shall be made by depositing
immediately available funds from the Escrow Account equal to the Mandatory
Redemption Price with the Paying Agent on the Mandatory Redemption Payment Date.
The Trustee or the Paying Agent shall promptly return to the Company any money
deposited with the Trustee or the Paying Agent by the Company in excess of the
amounts necessary to pay the Mandatory Redemption Price. The Trustee shall give
the notice of redemption to each Holder of Notes in the Company's name and at
its expense at least one Business Day prior to the Mandatory Redemption Date
setting forth the applicable information required to be provided to the Holders
of the Notes under Section 3.03 hereof. Once such notice is provided, the Notes
shall become irrevocably due and payable on the Mandatory Redemption Date at the
Mandatory Redemption Price.

                                       46

<PAGE>

        (c)     Except as provided in clauses (a) and (b) of this Section 3.08,
the Company shall not be required to make mandatory redemption or sinking fund
payments with respect to the Notes.

        Section 3.09.   Offer to Purchase by Application of Excess Proceeds.

        In the event that, pursuant to Section 4.10 hereof, the Company shall be
required to commence an offer to all Holders to purchase Notes (an "Asset Sale
Offer"), it shall follow the procedures specified below.

        The Asset Sale Offer shall remain open for a period of 20 Business Days
following its commencement and no longer, except to the extent that a longer
period is required by applicable law (the "Offer Period"). No later than five
Business Days after the termination of the Offer Period (the "Purchase Date"),
the Company shall purchase the Accreted Value of the Notes and the aggregate
principal amount (or accreted value, as applicable) of other senior subordinated
Indebtedness of the Company required to be purchased pursuant to Section 4.10
hereof (on a pro rata basis if Notes and other senior subordinated Indebtedness
of the Company tendered are in excess of the Excess Proceeds) (which maximum
amount shall be the "Offer Amount") or, if less than the Offer Amount has been
tendered, all Notes and other senior subordinated Indebtedness tendered in
response to the Asset Sale Offer. Payment for any Notes so purchased shall be
made pursuant to Section 4.01 hereof.

        Upon the commencement of an Asset Sale Offer, the Company shall send, by
first class mail, a notice to the Trustee and each of the Holders, with a copy
to the Trustee. The notice shall contain all instructions and materials
necessary to enable such Holders to tender Notes pursuant to the Asset Sale
Offer. The Asset Sale Offer shall be made to all Holders. The notice, which
shall govern the terms of the Asset Sale Offer, shall state:

                (i)     that the Asset Sale Offer is being made pursuant to this
                        Section 3.09 and Section 4.10 hereof and the length of
                        time the Asset Sale Offer shall remain open;

                (ii)    the Offer Amount, the purchase price and the Purchase
                        Date;

                (iii)   that the Accreted Value of any Note not tendered or
                        accepted for payment shall continue to increase;

                (iv)    that the Accreted Value of any Note accepted for payment
                        pursuant to the Asset Sale Offer shall cease to increase
                        after the Purchase Date;

                (v)     that Holders electing to have a Note purchased pursuant
                        to an Asset Sale Offer may elect to have Notes purchased
                        in integral multiples of $1,000 only;

                (vi)    that Holders electing to have a Note purchased pursuant
                        to any Asset Sale Offer shall be required to surrender
                        the Note, with the form entitled

                                       47

<PAGE>

                        "Option of Holder to Elect Purchase" on the reverse of
                        the Note completed, or transfer by book-entry transfer,
                        to the Company, a Depositary, if appointed by the
                        Company, or a Paying Agent at the address specified in
                        the notice at least three days before the Purchase Date;

                (vii)   that Holders shall be entitled to withdraw their
                        election if the Company, the Depositary or the Paying
                        Agent, as the case may be, receives, not later than the
                        expiration of the Offer Period, a telegram, telex,
                        facsimile transmission or letter setting forth the name
                        of the Holder, the principal amount at maturity of the
                        Note the Holder delivered for purchase and a statement
                        that such Holder is withdrawing his election to have
                        such Note purchased;

                (viii)  that, if the aggregate Accreted Value of the Notes and
                        the principal amount (or accreted value, as applicable)
                        of other senior subordinated Indebtedness of the Company
                        surrendered exceeds the Offer Amount, the Company shall
                        select the Notes to be purchased on a pro rata basis
                        (with such adjustments as may be deemed appropriate by
                        the Company so that only Notes in denominations of
                        $1,000, or integral multiples thereof, shall be
                        purchased); and

                (ix)    that Holders whose Notes were purchased only in part
                        shall be issued new Notes equal in principal amount at
                        maturity to the unpurchased portion of the Notes
                        surrendered (or transferred by book-entry transfer).

        On or before the Purchase Date, the Company shall, to the extent lawful,
accept for payment, on a pro rata basis to the extent necessary, the Offer
Amount of Notes or portions thereof tendered pursuant to the Asset Sale Offer,
or if less than the Offer Amount has been tendered, all Notes and other senior
subordinated Indebtedness tendered, and shall deliver to the Trustee an
Officers' Certificate stating that the Notes or portions thereof were accepted
for payment by the Company in accordance with the terms of this Section 3.09.
The Company, the Depositary or the Paying Agent, as the case may be, shall
promptly (but in any case not later than five days after the Purchase Date) mail
or deliver to each tendering Holder an amount equal to the purchase price of the
Notes tendered by such Holder and accepted by the Company for purchase, and the
Company shall promptly issue a new Note, and the Trustee, upon written request
from the Company shall authenticate and mail or deliver such new Note to such
Holder, in a principal amount at maturity equal to any unpurchased portion of
the Note surrendered. Any Note not so accepted shall be promptly mailed or
delivered by the Company to the Holder thereof. The Company shall publicly
announce the results of the Asset Sale Offer on the Purchase Date.

        The Company shall comply with the requirements of Section 14(e) of the
Exchange Act and any other securities laws or regulations to the extent those
laws and regulations are applicable to any Asset Sale Offer. If the provisions
of any of the applicable securities laws or securities regulations conflict with
the provisions of this Section 3.09, the Company shall comply

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<PAGE>

with the applicable securities laws and regulations and shall not be deemed to
have breached its obligations under this Section 3.09 by virtue of the
compliance.

        Other than as specifically provided in this Section 3.09, any purchase
pursuant to this Section 3.09 shall be made pursuant to the provisions of
Sections 3.01 through 3.06 hereof.

        The provisions under this Indenture relating to the Company's obligation
to make an Asset Sale Offer may be waived or modified with the written consent
of the Holders of at least a majority in principal amount at maturity of the
Notes then outstanding.

                                    ARTICLE 4

                                    COVENANTS

        Section 4.01.   Payment of Notes.

        The Company shall pay or cause to be paid the Accreted Value of,
Liquidated Damages and premium, if any, on the Notes on the dates and in the
manner provided in the Notes. Accreted Value and premium, if any, shall be
considered paid on the date due if the Paying Agent, if other than the Company
or a Subsidiary thereof, holds as of 10:00 a.m., Eastern Time, on the due date
money deposited by the Company in immediately available funds and designated for
and sufficient to pay all Accreted Value and premium, if any, then due. The
Company shall pay all Liquidated Damages, if any, in the same manner on the
dates and in the amounts set forth in the Registration Rights Agreement.

        The Company shall pay interest (including post-petition interest in any
proceeding under any Bankruptcy Law) on overdue Accreted Value and premium, if
any, at a rate equal to 1% per annum in excess of the then applicable rate of
accretion of the Notes, to the extent lawful. The accrual of such interest on
overdue amounts shall be in lieu of, and not in addition to, the continued
increase of Accreted Value.

        Section 4.02.   Maintenance of Office or Agency.

        The Company shall maintain in the Borough of Manhattan, The City of New
York, an office or agency (which may be an office of the Trustee or an affiliate
of the Trustee, Registrar or co-registrar) where Notes may be surrendered for
registration of transfer or for exchange and where notices and demands to or
upon the Company in respect of the Notes and this Indenture may be served. The
Company shall give prompt written notice to the Trustee of the location, and any
change in the location, of such office or agency. If at any time the Company
shall fail to maintain any such required office or agency or shall fail to
furnish the Trustee with the address thereof, such presentations, surrenders,
notices and demands may be made or served at the Corporate Trust Office of the
Trustee.

        The Company may also from time to time designate one or more other
offices or agencies where the Notes may be presented or surrendered for any or
all such purposes and may from time to time rescind such designations; provided,
however, that no such designation or rescission

                                       49

<PAGE>

shall in any manner relieve the Company of its obligation to maintain an office
or agency in the Borough of Manhattan, The City of New York, for such purposes.
The Company shall give prompt written notice to the Trustee of any such
designation or rescission and of any change in the location of any such other
office or agency.

        The Company hereby designates the Corporate Trust Office of the Trustee
as one such office or agency of the Company in accordance with Section 2.03
hereof.

        Section 4.03.   Reports.

        Whether or not required by the SEC, so long as any Notes are
outstanding, the Company shall furnish to the Holders of Notes:

                        (1)     all quarterly and annual financial information
                                of the Parent that would be required to be
                                contained in a filing with the SEC on Forms 10-Q
                                and 10-K if the Parent were required to file
                                such Forms, and, with respect to the annual
                                information only, a report on the annual
                                financial statements by the Parent's certified
                                independent accountants;

                        (2)     the Tower Cash Flow for the most recently
                                completed fiscal quarter and the Adjusted
                                Consolidated Cash Flow and Non-Tower Cash Flow
                                for the most recently completed four-quarter
                                period, in each case of the Parent; and

                        (3)     all current reports that would be required to be
                                filed with the SEC on Form 8-K if the Parent
                                were required to file such reports.

        in each case within the time periods specified in the SEC's rules and
regulations.

        If the Company or a Sister Guarantor has designated any of its
respective Subsidiaries as Unrestricted Subsidiaries and any such Unrestricted
Subsidiary (or group of Unrestricted Subsidiaries) is a Significant Subsidiary,
then the quarterly and annual financial information required by the preceding
paragraph shall include a reasonably detailed presentation, either on the face
of the financial statements or in the footnotes thereto, and in Management's
Discussion and Analysis of Financial Condition and Results of Operations, of the
financial condition and results of operations of the Company and its Restricted
Subsidiaries separate from the financial condition and results of operations of
the Unrestricted Subsidiaries of the Company. The Company may furnish the
foregoing required information to the Holders of the Notes supplementally in
Parent's reports consistent with Rule 3-10 of Regulation S-X and not include
such information in Company reports filed with the SEC. In no event shall the
foregoing required information apply to any discontinued operations.

        In addition, following the consummation of the Exchange Offer
contemplated by the Registration Rights Agreement, whether or not required by
the SEC, all of the information and reports referred to in clauses (1) through
(3) above shall be filed with the SEC for public

                                       50

<PAGE>

availability within the time periods specified in the SEC's rules and
regulations (unless the SEC shall not accept such a filing) and make such
information available to securities analysts and prospective investors upon
request. In addition, the Company and the Guarantors have agreed that, for so
long as any Notes (but not Exchange Notes) remain outstanding, they shall
furnish to the Holders and to securities analysts and prospective investors,
upon their request, the information required to be delivered pursuant to Rule
144A(d)(4) under the Securities Act.

        In the event that the Company is at any time required by the SEC to file
reports under the Exchange Act, the Company shall, so long as any Notes (but not
Exchange Notes) are outstanding furnish to the Holders of Notes, within the time
periods specified in the SEC's rules and regulations, the foregoing required
information.

        Section 4.04.   Compliance Certificate.

                (1)     The Company shall deliver to the Trustee, within 90 days
                        after the end of each fiscal year, an Officers'
                        Certificate stating that a review of the activities of
                        the Company and its Subsidiaries during the preceding
                        fiscal year has been made under the supervision of the
                        signing Officers with a view to determining whether the
                        Company has kept, observed, performed and fulfilled its
                        obligations under this Indenture, and further stating,
                        as to each such Officer signing such certificate, that
                        to the best of his or her knowledge the Company has
                        kept, observed, performed and fulfilled each and every
                        covenant contained in this Indenture and is not in
                        default in the performance or observance of any of the
                        terms, provisions and conditions of this Indenture (or,
                        if a Default or Event of Default shall have occurred,
                        describing all such Defaults or Events of Default of
                        which he or she may have knowledge and what action the
                        Company is taking or proposes to take with respect
                        thereto).

                (2)     The Company shall, so long as any of the Notes are
                        outstanding, deliver to the Trustee, forthwith upon any
                        Officer becoming aware of any Default or Event of
                        Default, an Officers' Certificate specifying such
                        Default or Event of Default and what action the Company
                        is taking or proposes to take with respect thereto.

        Section 4.05.   Taxes.

        The Company shall pay, and shall cause each of its Subsidiaries to pay,
prior to delinquency, all material taxes, assessments, and governmental levies
except such as are contested in good faith and by appropriate proceedings or
where the failure to effect such payment is not adverse in any material respect
to the Holders of the Notes.

        Section 4.06.   Stay, Extension and Usury Laws.

        The Company covenants (to the extent that it may lawfully do so) that it
shall not at any time insist upon, plead, or in any manner whatsoever claim or
take the benefit or advantage of,

                                       51

<PAGE>

any stay, extension or usury law wherever enacted, now or at any time hereafter
in force, that may affect the covenants or the performance of this Indenture;
and the Company (to the extent that it may lawfully do so) hereby expressly
waives all benefit or advantage of any such law, and covenants that it shall
not, by resort to any such law, hinder, delay or impede the execution of any
power herein granted to the Trustee, but shall suffer and permit the execution
of every such power as though no such law has been enacted.

        Section 4.07.   Restricted Payments.

        The Company and each Sister Guarantor shall not, and each of them shall
not permit any of their respective Restricted Subsidiaries to, directly or
indirectly:

                (1)     declare or pay any dividend or make any other payment or
                        distribution on account of the Company's, any Sister
                        Guarantor's or any of the Restricted Subsidiaries'
                        Equity Interests (including, without limitation, any
                        payment in connection with any merger or consolidation
                        involving the Company, any Sister Guarantor or any of
                        the Restricted Subsidiaries) or to the direct or
                        indirect holders of the Company's, any Sister
                        Guarantor's or any of the Restricted Subsidiaries'
                        Equity Interests in their capacity as such (other than
                        dividends or distributions payable in Equity Interests
                        (other than Disqualified Stock) of the Company or a
                        Sister Guarantor or to the Company or a Sister Guarantor
                        or a Restricted Subsidiary);

                (2)     purchase, redeem or otherwise acquire or retire for
                        value (including, without limitation, in connection with
                        any merger or consolidation involving the Company or a
                        Sister Guarantor, as the case may be) any Equity
                        Interests of the Company or a Sister Guarantor or of any
                        Person of which the Company or a Sister Guarantor is a
                        Subsidiary (other than any such Equity Interests owned
                        by the Company, a Sister Guarantor or any of the
                        Restricted Subsidiaries);

                (3)     make any payment on or with respect to, or purchase,
                        redeem, defease or otherwise acquire or retire for value
                        any Indebtedness that is subordinated to the Notes or
                        the Note Guarantees, except a payment of interest or
                        principal at the Stated Maturity thereof (other than
                        payments to the Company or a Sister Guarantor or
                        payments by a Restricted Subsidiary to the Company or a
                        Sister Guarantor or to another Restricted Subsidiary);
                        or

                (4)     make any Restricted Investment,

(all such payments and other actions set forth in these clauses (1) through (4)
above, being collectively referred to as "Restricted Payments"),

        unless, at the time of and after giving effect to such Restricted
Payment:

                                       52

<PAGE>

                (1)     no Default or Event of Default has occurred and is
                        continuing or would occur as a consequence of such
                        Restricted Payment; and

                (2)     the Parent, at the time of such Restricted Payment and
                        after giving pro forma effect thereto as if such
                        Restricted Payment had been made at the beginning of the
                        applicable four-quarter period, would have had a Debt to
                        Adjusted Consolidated Cash Flow Ratio no greater than
                        7.5 to 1.0; provided that this clause (2) shall not
                        apply in connection with any Restricted Investment; and

                (3)     such Restricted Payment, together with the aggregate
                        amount of all other Restricted Payments made by the
                        Company, the Sister Guarantors and the Restricted
                        Subsidiaries after the Issue Date (excluding Restricted
                        Payments permitted by clauses (2), (3), (4) and (6)) of
                        the next succeeding paragraph), is less than the sum,
                        without duplication, of:

                        (a)     100% of the Consolidated Cash Flow of the Parent
                                for the period (taken as one accounting period)
                                from the beginning of the fiscal quarter during
                                which the Issue Date falls to the end of the
                                Company's most recently ended fiscal quarter for
                                which internal financial statements are
                                available at the time of such Restricted Payment
                                (or, if the Consolidated Cash Flow for such
                                period is a deficit, less 100% of the deficit),
                                less 1.4 times the Consolidated Interest Expense
                                of the Parent since the beginning of the fiscal
                                quarter during which the Issue Date falls to the
                                end of the Company's most recently ended fiscal
                                quarter for which internal financial statements
                                are available at the time of such Restricted
                                Payment, plus

                        (b)     (i) 100% of the aggregate net cash proceeds plus
                                (ii) 70% of the aggregate value, as reflected on
                                the balance sheets of the Company and the Sister
                                Guarantors in accordance with GAAP using
                                purchase accounting, of any Qualified Proceeds
                                valued as of the date the Company's or a Sister
                                Guarantor's Equity Interests were issued, sold
                                or exchanged therefor, in each case, received by
                                the Company or any Sister Guarantor since the
                                Issue Date as a contribution to its common
                                equity capital or from the issue, sale or
                                exchange of Equity Interests of the Company and
                                the Sister Guarantor (other than Disqualified
                                Stock) or from the issue or sale (whether before
                                or after the Issue Date) of Disqualified Stock
                                or debt securities of the Company or any Sister
                                Guarantor that have been converted after the
                                Issue Date into Equity Interests (other than
                                Equity Interests (or Disqualified Stock or

                                       53

<PAGE>

                                convertible debt securities) sold to or held by
                                a Subsidiary of the Company or of any Sister
                                Guarantor and other than Disqualified Stock or
                                convertible debt securities that have been
                                converted into Disqualified Stock); plus

                        (c)     to the extent that any Restricted Investment
                                that was made after the Issue Date is sold for
                                cash or otherwise liquidated or repaid for cash,
                                the lesser of (i) the cash return of capital
                                with respect to such Restricted Investment (less
                                the cost of disposition, if any) and (ii) the
                                initial amount of such Restricted Investment,
                                plus

                        (d)     to the extent that any Unrestricted Subsidiary
                                of the Company or any Sister Guarantor and all
                                of its Subsidiaries are designated as or become
                                Restricted Subsidiaries after the Issue Date,
                                the lesser of:

                                (A)      the fair market value of the
                                         Investments by the Company or the
                                         Sister Guarantors in such Subsidiaries
                                         as of the date they are designated or
                                         become Restricted Subsidiaries, or

                                (B)      the sum of: (x) the fair market value
                                         of the Investments by the Company and
                                         the Sister Guarantors in such
                                         Subsidiaries as of the date on which
                                         such Subsidiaries were most recently
                                         designated as Unrestricted
                                         Subsidiaries, and (y) the amount of any
                                         Investments made in such Subsidiaries
                                         subsequent to such designation as
                                         Unrestricted Subsidiaries (and treated
                                         as Restricted Payments or excluded from
                                         clause (3)(b) pursuant to the proviso
                                         of clause (2) of the next paragraph) by
                                         the Company, a Sister Guarantor or any
                                         Restricted Subsidiary; plus

                        (e)     100% of any dividends or other distributions
                                received by the Company, a Sister Guarantor or a
                                Restricted Subsidiary after the Issue Date from
                                an Unrestricted Subsidiary, to the extent that
                                such dividends were not otherwise included in
                                Consolidated Net Income of the Company and the
                                Sister Guarantors (on a combined basis) for such
                                period.

        The preceding provisions shall not prohibit:

                (1)     the payment of any dividend or the making of any
                        distribution within 60 days after the date of
                        declaration of the dividend or distribution, if at the
                        date of declaration the dividend payment or distribution
                        would have complied with the provisions of this
                        Indenture;

                (2)     (a) the making of any Investment or (b) the redemption,
                        repurchase, retirement, defeasance or other acquisition
                        of any subordinated Indebtedness or Equity Interests of
                        the Company or a Sister Guarantor, in the case of (a) or
                        (b), in exchange for, or out of the net cash proceeds
                        from

                                       54

<PAGE>

                        the substantially concurrent sale after the Issue Date
                        (other than to a Subsidiary of the Company or a Sister
                        Guarantor) of Equity Interests of the Company or of a
                        Sister Guarantor (other than any Disqualified Stock);
                        provided that, in each case, the amount of any net cash
                        proceeds (or other assets, as applicable) that are so
                        utilized shall be excluded from clause (3)(b) of the
                        preceding paragraph;

                (3)     the defeasance, redemption, repurchase or other
                        acquisition of subordinated Indebtedness of the Company
                        or any Group Guarantor with the net cash proceeds from
                        an incurrence of Permitted Refinancing Indebtedness;

                (4)     the payment of any dividend by a Restricted Subsidiary
                        to the holders of its Equity Interests on a pro rata
                        basis;

                (5)     the repurchase, redemption or other acquisition or
                        retirement for value of any Equity Interests of the
                        Parent, the Company, any Sister Guarantor or any
                        Restricted Subsidiary held by any member of the
                        Parent's, the Company's or any Sister Guarantor's (or
                        any of the Restricted Subsidiaries') management pursuant
                        to any management equity subscription agreement,
                        stockholders agreement, stock option agreement or
                        restricted stock agreement in effect as of the Issue
                        Date; provided that the aggregate price paid for all
                        such repurchased, redeemed, acquired or retired Equity
                        Interests may not exceed $500,000 in any twelve-month
                        period and $5.0 million in the aggregate since the Issue
                        Date; and

                (6)     any dividend, payment, advance or distribution made to
                        the Parent, (i) which is applied by Parent to pay
                        scheduled interest, dividends or principal or premium or
                        liquidation preference at the Stated Maturity thereof or
                        pursuant to a mandatory redemption or repurchase
                        obligation on the Existing Parent Indebtedness or
                        Additional Parent Indebtedness, (ii) in an amount equal
                        to up to $217 million to be used for purposes described
                        under the caption "Use of Proceeds" in the Offering
                        Circular, or (iii) in accordance with clause (7) of the
                        second paragraph of Section 4.11 hereof.

        The amount of all Restricted Payments (other than cash) shall be the
fair market value on the date of the Restricted Payment of the asset(s) or
securities proposed to be transferred or issued by the Company, such Sister
Guarantor or such Restricted Subsidiary, as the case may be, pursuant to the
Restricted Payment.

        The fair market value of any assets or securities that are required to
be valued by this Section shall be determined by the Board of Directors whose
resolution with respect thereto shall be delivered to the Trustee. Not later
than the date of making any Restricted Payment, the Company shall deliver to the
Trustee an Officers' Certificate stating that such Restricted Payment is
permitted and setting forth the basis upon which the calculations required by
this

                                       55

<PAGE>

Section 4.07 were computed, together with a copy of any fairness opinion or
appraisal required by this Indenture.

        Section 4.08.   Dividend and Other Payment Restrictions Affecting
                        Subsidiaries.

        The Company and each Sister Guarantor shall not, and shall not permit
any of their respective Restricted Subsidiaries to, directly or indirectly,
create or permit to exist or become effective any encumbrance or restriction on
the ability of any Restricted Subsidiary to:

                (1)     pay dividends or make any other distributions on its
                        Capital Stock to the Company, any Sister Guarantor or
                        any of the Restricted Subsidiaries, or with respect to
                        any other interest or participation in, or measured by,
                        its profits;

                (2)     pay any Indebtedness owed to the Company, any Sister
                        Guarantor or any of the Restricted Subsidiaries;

                (3)     make loans or advances to the Company, any Sister
                        Guarantor or any of the Restricted Subsidiaries; or

                (4)     transfer any of its properties or assets to the Company,
                        any Sister Guarantor or any of the Restricted
                        Subsidiaries.

        However, the preceding restrictions shall not apply to encumbrances or
restrictions existing under or by reason of:

                (1)     agreements governing Existing Indebtedness as in effect
                        on the Issue Date and any amendments, modifications,
                        restatements, renewals, increases, supplements,
                        refundings, replacements or refinancings thereof,
                        provided that the amendments, modifications,
                        restatements, renewals, increases, supplements,
                        refundings, replacement or refinancings are no more
                        restrictive, taken as a whole, with respect to such
                        dividend and other payment restrictions than those
                        contained in those agreements on the Issue Date unless
                        such restrictions are ordinary and customary for
                        agreements of that type as determined in the good faith
                        judgment of the Company's Board of Directors (and
                        evidenced in a board resolution), which determination
                        shall be conclusively binding;

                (2)     Indebtedness of the Company, any Sister Guarantor or any
                        Restricted Subsidiary under any Credit Facility that is
                        permitted to be incurred pursuant to Section 4.09
                        hereof; provided that such Credit Facility and
                        Indebtedness contain only such encumbrances and
                        restrictions on such Restricted Subsidiary's ability to
                        engage in the activities set forth in clauses (1)
                        through (4) of the preceding paragraph as are, at the
                        time such Credit Facility is entered into or amended,
                        modified, restated, renewed, increased, supplemented,
                        refunded, replaced or refinanced, ordinary and

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<PAGE>

                        customary for a Credit Facility of that type as
                        determined in the good faith judgment of the Company's
                        Board of Directors (and evidenced in a board
                        resolution), which determination shall be conclusively
                        binding;

                (3)     encumbrances and restrictions applicable to any
                        Unrestricted Subsidiary, as the same are in effect as of
                        the date on which the Subsidiary becomes a Restricted
                        Subsidiary, and as the same may be amended, modified,
                        restated, renewed, increased, supplemented, refunded,
                        replaced or refinanced; provided that such amendments,
                        modifications, restatements, renewals, increases,
                        supplements, refundings, replacement or refinancings are
                        no more restrictive, taken as a whole, with respect to
                        the dividend and other payment restrictions than those
                        contained in the applicable series of Indebtedness of
                        such Subsidiary as in effect on the date on which such
                        Subsidiary becomes a Restricted Subsidiary unless such
                        restrictions are ordinary and customary for agreements
                        of that type as determined in the good faith judgment of
                        the Company's Board of Directors (and evidenced in a
                        board resolution), which determination shall be
                        conclusively binding;

                (4)     any Indebtedness incurred in compliance with Section
                        4.09 hereof or any agreement pursuant to which such
                        Indebtedness is issued if the encumbrance or restriction
                        applies only in the event of a payment default or
                        default with respect to a financial covenant contained
                        in the Indebtedness or agreement and the encumbrance or
                        restriction is not materially more disadvantageous to
                        the Holders of the Notes than is customary in comparable
                        financings (as determined by the Company) and the
                        Company determines that any such encumbrance or
                        restriction will not materially affect the Company's
                        ability to pay the Accreted Value of the Notes;

                (5)     this Indenture, the Notes and the Note Guarantees;

                (6)     applicable law;

                (7)     any instrument governing Indebtedness or Capital Stock
                        of a Person acquired by the Company, any Sister
                        Guarantor or any of the Restricted Subsidiaries as in
                        effect at the time of such acquisition (except to the
                        extent such Indebtedness or Capital Stock was incurred
                        in connection with or in contemplation of such
                        acquisition), which encumbrance or restriction is not
                        applicable to any Person, or the properties or assets of
                        any Person, other than the Person, or the property or
                        assets of the Person, so acquired, and as such
                        instrument may be amended, modified, restated, renewed,
                        increased, supplemented, refunded, replaced or
                        refinanced, provided that, in the case of Indebtedness,
                        such Indebtedness was permitted by the terms of this
                        Indenture to be incurred and, provided further, that any
                        such amendment, modification, restatement, renewal,
                        increase, supplement,

                                       57

<PAGE>

                        refunding, replacement or refinancing is no more
                        restrictive, taken as a whole, with respect to the
                        dividend and other payment restrictions than those
                        contained in the instrument as in effect on the date on
                        which the Person was acquired by the Company unless such
                        restrictions are ordinary and customary for agreements
                        of that type as determined in the good faith judgment of
                        the Company's Board of Directors (and evidenced in a
                        board resolution), which determination shall be
                        conclusively binding;

                (8)     customary non-assignment provisions in leases or
                        licenses entered into in the ordinary course of
                        business;

                (9)     purchase money obligations for property acquired in the
                        ordinary course of business that impose restrictions of
                        the nature described in clause (4) in the second
                        paragraph of Section 4.09 hereof on the property so
                        acquired;

                (10)    any agreement for the sale or other disposition of a
                        Restricted Subsidiary that restricts that Restricted
                        Subsidiary pending its sale or other disposition;

                (11)    Permitted Refinancing Indebtedness, provided that the
                        restrictions contained in the agreements governing such
                        Permitted Refinancing Indebtedness are no more
                        restrictive, taken as a whole, than those contained in
                        the agreements governing the Indebtedness being
                        refinanced unless such restrictions are ordinary and
                        customary for agreements of that type as determined in
                        the good faith judgment of the Company's Board of
                        Directors (and evidenced in a board resolution), which
                        determination shall be conclusively binding;

                (12)    Liens permitted to be incurred pursuant to the
                        provisions of Section 4.12 hereof that limit the right
                        of the debtor to transfer the assets subject to such
                        Liens;

                (13)    provisions with respect to the disposition or
                        distribution of assets or property in joint venture
                        agreements and other similar agreements; and

                (14)    restrictions on cash or other deposits or net worth
                        imposed by customers under contracts entered into in the
                        ordinary course of business.

        Section 4.09.   Incurrence of Indebtedness and Issuance of Preferred
                        Stock.

        The Company and each Sister Guarantor shall not, and shall not permit
any of their respective Restricted Subsidiaries to, directly or indirectly,
create, incur, issue, assume, guarantee or otherwise become directly or
indirectly liable, contingently or otherwise, with respect to (collectively,
"incur") any Indebtedness (including Acquired Debt), and the Company and each
Sister Guarantor shall not issue any Disqualified Stock and shall not permit any
of their respective Restricted Subsidiaries to issue any shares of preferred
stock.

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<PAGE>

        The provisions of the first paragraph of this Section 4.09 shall not
prohibit the incurrence of any of the following items of Indebtedness or the
issuance of any of the following items of Disqualified Stock or preferred stock
(collectively, "Permitted Debt"):

                (1)     the incurrence by the Company, any Sister Guarantor or
                        any of the Restricted Subsidiaries of Indebtedness under
                        Credit Facilities in an aggregate principal amount (with
                        letters of credit being deemed to have a principal
                        amount equal to the maximum potential liability of the
                        Company, the Sister Guarantors and the Restricted
                        Subsidiaries thereunder) incurred under this clause (1)
                        at any one time outstanding not to exceed $1.6 billion
                        less any amount applied to reduce Indebtedness incurred
                        under this clause (1) as a result of the operation of
                        clause (1) of the second paragraph of Section 4.10
                        hereof;

                (2)     the incurrence by the Company, the Sister Guarantors and
                        the Restricted Subsidiaries of the Existing
                        Indebtedness;

                (3)     the incurrence by the Company and the Group Guarantors
                        of Indebtedness represented by the Notes and the related
                        Note Guarantees and the Exchange Notes and the related
                        Note Guarantees to be issued pursuant to the
                        Registration Rights Agreement;

                (4)     the incurrence by the Company, any Sister Guarantor or
                        any of the Restricted Subsidiaries of Indebtedness:

                        (a)     represented by Capital Lease Obligations
                        incurred (i) in connection with the lease or other use
                        of space or time on satellites or (ii) for the purpose
                        of financing all or any part of the purchase price or
                        cost of construction or improvement of property, plant
                        or equipment, in each case used in the Teleports
                        Business of the Company, such Sister Guarantor or such
                        Restricted Subsidiary or

                        (b)     represented by Capital Lease Obligations,
                        mortgage financings or purchase money obligations, in
                        each case, incurred for the purpose of financing all or
                        any part of the purchase price or cost of construction
                        or improvement of property, plant or equipment used in
                        the business of the Company, such Sister Guarantor or
                        such Restricted Subsidiary, in an aggregate principal
                        amount, including all Permitted Refinancing Indebtedness
                        incurred to refund, refinance or replace any
                        Indebtedness incurred pursuant to this clause (4), not
                        to exceed $50.0 million at any time outstanding;

                (5)     the incurrence by the Company, any Sister Guarantor or
                        any of the Restricted Subsidiaries of Permitted
                        Refinancing Indebtedness in exchange for, or the net
                        proceeds of which are used to extend, refinance, renew,
                        replace, defease or refund Indebtedness (other than
                        intercompany

                                       59

<PAGE>

                        Indebtedness) or preferred stock or Disqualified Stock
                        that was permitted by this Indenture to be incurred
                        under clauses (2), (3), (4), (5) or (11) of this
                        paragraph;

                (6)     the incurrence by the Company, any Sister Guarantor or
                        any of the Restricted Subsidiaries of intercompany
                        Indebtedness between or among the Company, any Sister
                        Guarantor and any of the Restricted Subsidiaries and the
                        issuance by any Restricted Subsidiary of shares of
                        preferred stock to the Company, a Sister Guarantor or to
                        another Restricted Subsidiary; provided, however, that:

                        (a)     if the Company or any Group Guarantor is the
                        obligor on such Indebtedness, such Indebtedness must be
                        expressly subordinated to the prior payment in full in
                        cash of all obligations with respect to the Notes, in
                        the case of the Company, or the Note Guarantee, in the
                        case of a Group Guarantor; and

                        (b)     (i) any subsequent issuance or transfer of
                        Equity Interests that results in any such Indebtedness
                        or preferred stock being held by a Person other than the
                        Company, a Sister Guarantor or a Restricted Subsidiary
                        and (ii) any sale or other transfer of any such
                        Indebtedness or preferred stock to a Person that is not
                        either the Company, a Sister Guarantor or a Restricted
                        Subsidiary shall be deemed, in each case, to constitute
                        an incurrence of such Indebtedness by the Company, such
                        Sister Guarantor or such Restricted Subsidiary or
                        issuance of the shares of preferred stock by such
                        Restricted Subsidiary, as the case may be, that was not
                        permitted by this clause (6);

                (7)     the incurrence by the Company, any Sister Guarantor or
                        any of the Restricted Subsidiaries of Hedging
                        Obligations that are incurred for the purpose of fixing
                        or hedging interest rate risk with respect to any
                        floating rate Indebtedness that is permitted by the
                        terms of this Indenture to be outstanding or currency
                        exchange risk;

                (8)     the Guarantee by the Company or any of the Group
                        Guarantors of Indebtedness of the Company, a Sister
                        Guarantor or a Restricted Subsidiary that was permitted
                        to be incurred by another provision of this Indenture;

                (9)     the accrual of interest, the accretion or amortization
                        of original issue discount, the payment of interest on
                        any Indebtedness in the form of additional Indebtedness
                        with the same terms, and the payment of dividends on
                        preferred stock or Disqualified Stock in the form of
                        additional shares of the same class of preferred stock
                        or Disqualified Stock shall not be deemed to be an
                        incurrence of Indebtedness or an issuance of preferred
                        stock or Disqualified Stock for purposes of this Section
                        4.09;

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<PAGE>

                        provided, in each such case, that the amount thereof is
                        included in Consolidated Interest Expense of the Company
                        and the Sister Guarantors as accrued;

                (10)    the incurrence by the Company, any Sister Guarantor or
                        any of the Restricted Subsidiaries of Acquired Debt in
                        connection with a merger with or into a Restricted
                        Subsidiary, or the acquisition of assets or a new
                        Subsidiary; provided that, in the case of any such
                        incurrence of Acquired Debt, such Acquired Debt was
                        incurred by the prior owner of such assets or such
                        Restricted Subsidiary prior to such acquisition by the
                        Company, a Sister Guarantor or one of the Restricted
                        Subsidiaries and was not incurred in connection with, or
                        in contemplation of, the acquisition by the Company, a
                        Sister Guarantor or one of the Restricted Subsidiaries;
                        and provided further that, in the case of any incurrence
                        pursuant to this clause (10), as a result of such
                        acquisition by the Company, a Sister Guarantor or one of
                        the Restricted Subsidiaries, the Debt to Adjusted
                        Consolidated Cash Flow Ratio of the Parent at the time
                        of incurrence of such Acquired Debt, after giving pro
                        forma effect to such acquisition and incurrence as if
                        the same had occurred at the beginning of the most
                        recently ended four full fiscal quarter period of the
                        Company for which internal financial statements are
                        available, would have been the same or less than the
                        Debt to Adjusted Consolidated Cash Flow Ratio of the
                        Parent for the same period without giving pro forma
                        effect to such incurrence; and

                (11)    the incurrence by the Company, any Sister Guarantor or
                        any of the Restricted Subsidiaries of additional
                        Indebtedness and/or the issuance of preferred stock or
                        Disqualified Stock in an aggregate principal amount (or
                        accreted value or liquidation preference, as applicable)
                        at any time outstanding, including Indebtedness incurred
                        to refund, refinance or replace any Indebtedness
                        incurred pursuant to this clause (11), not to exceed
                        $25.0 million.

        For purposes of determining compliance with this Section 4.09, in the
event that an item of Indebtedness meets the criteria of more than one of the
categories of Permitted Debt described in clauses (1) through (11) above, the
Company and the Sister Guarantors shall be permitted to classify such item of
Indebtedness on the date of its incurrence, or later reclassify all or a portion
of such item of Indebtedness, in any manner that complies with this Section
4.09. Indebtedness under the Credit Agreement outstanding on the date on which
Notes are first issued and authenticated under this Indenture shall be deemed to
have been incurred on such date in reliance on the exception provided by clause
(1) of the definition of Permitted Debt.

        Section 4.10.   Asset Sales.

        The Company and each Sister Guarantor shall not, and shall not permit
any of its respective Restricted Subsidiaries to, consummate an Asset Sale
unless:

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<PAGE>

                (1)     the Company, Sister Guarantor or Restricted Subsidiary,
                        as the case may be, receives consideration at the time
                        of the Asset Sale at least equal to the fair market
                        value of the assets or Equity Interests issued or sold
                        or otherwise disposed of;

                (2)     the fair market value is determined by the Company's
                        Board of Directors and evidenced by a resolution of the
                        Company's Board of Directors set forth in an Officers'
                        Certificate delivered to the Trustee; and

                (3)     except in the case of a Tower Asset Exchange, a Surplus
                        Asset Sale or an Excluded International Sale, at least
                        75% of the consideration received in such Asset Sale by
                        the Company, the Sister Guarantor or Restricted
                        Subsidiary is in the form of cash or Cash Equivalents.
                        For purposes of this provision, each of the following
                        shall be deemed to be cash:

                        (a)     any liabilities of the Company, the Sister
                        Guarantor or Restricted Subsidiary, as the case may be,
                        as shown on its most recent balance sheet (other than
                        contingent liabilities and liabilities that are by their
                        terms subordinated to the Notes or any Note Guarantee)
                        that are assumed by the transferee of any assets
                        pursuant to a customary novation agreement that releases
                        the Company, the Sister Guarantor or the Restricted
                        Subsidiary from further liability; and

                        (b)     any securities, notes or other obligations
                        received by the Company, the Sister Guarantor or the
                        Restricted Subsidiary, as the case may be, from the
                        transferee that are converted by the Company, the Sister
                        Guarantor or the Restricted Subsidiary into cash within
                        20 days of the applicable Asset Sale, to the extent of
                        the cash received in that conversion.

        Within 365 days after the receipt of any Net Proceeds from an Asset
Sale, the Company, the Sister Guarantor or the Restricted Subsidiary, as the
case may be, may apply those Net Proceeds at its option:

                (1)     to repay Senior Debt and, if the Senior Debt repaid is
                        revolving credit Indebtedness, to correspondingly reduce
                        commitments with respect thereto;

                (2)     to repay other Indebtedness of any of the Sister
                        Guarantors or Restricted Subsidiaries;

                (3)     to acquire all or substantially all of the assets of, or
                        a majority of the Voting Stock or other Equity Interests
                        of, another Permitted Business;

                (4)     to make a capital expenditure; or

                (5)     to acquire other assets that are used or useful in a
                        Permitted Business.

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<PAGE>

        Pending the final application of any Net Proceeds, they can be used to
temporarily reduce revolving credit borrowings or otherwise be invested in any
manner that is not prohibited by this Indenture.

        Any Net Proceeds from Asset Sales that are not applied or invested as
provided in the preceding paragraph shall constitute "Excess Proceeds." When the
aggregate amount of Excess Proceeds exceeds $10.0 million, the Company shall
make an Asset Sale Offer to all Holders of Notes and all holders of other
Indebtedness that is pari passu with the Notes containing provisions similar to
those set forth in this Indenture with respect to offers to purchase or redeem
with the proceeds of sales of assets to purchase the maximum principal amount at
maturity of Notes and such other pari passu Indebtedness that may be purchased
out of the Excess Proceeds. The offer price in any Asset Sale Offer for Notes
shall be equal to 100% of the Accreted Value thereof and Liquidated Damages, if
any, to the date of purchase, and shall be payable in cash. If any Excess
Proceeds remain after consummation of an Asset Sale Offer, those Excess Proceeds
may be used for any purpose not otherwise prohibited by this Indenture. If the
aggregate Accreted Value of Notes and other pari passu Indebtedness tendered
into such Asset Sale Offer exceeds the amount of Excess Proceeds, the Trustee
shall select the Notes and such other pari passu Indebtedness to be purchased on
a pro rata basis. Upon completion of each Asset Sale Offer, the amount of Excess
Proceeds shall be reset to zero.

        Section 4.11.   Transactions with Affiliates.

        The Company and each Sister Guarantor shall not, and shall not permit
any of their respective Restricted Subsidiaries to, make any payment to, or
sell, lease, transfer or otherwise dispose of any of its properties or assets
to, or purchase any property or assets from, or enter into or make or amend any
transaction, contract, agreement, understanding, loan, advance or Guarantee
with, or for the benefit of, any Affiliate (each, an "Affiliate Transaction"),
unless:

                (1)     the Affiliate Transaction is on terms that, in the
                        aggregate, are no less favorable to the Company, the
                        relevant Sister Guarantor or the relevant Restricted
                        Subsidiary than those that would have been obtained in a
                        comparable transaction by the Company, such Sister
                        Guarantor or such Restricted Subsidiary with an
                        unrelated Person; and

                (2)     the Company delivers to the Trustee:

                        (a)     with respect to any Affiliate Transaction or
                                series of related Affiliate Transactions
                                involving aggregate consideration in excess of
                                $5.0 million, an Officers' Certificate
                                certifying that the Affiliate Transaction
                                complies with clause (1) above;

                        (b)     with respect to any Affiliate Transaction or
                                series of related Affiliate Transactions
                                involving aggregate consideration in excess of
                                $10.0 million, a resolution of the Company's
                                Board of Directors set forth in an Officers'
                                Certificate certifying that such Affiliate
                                Transaction complies with clause (1) above and
                                that such Affiliate

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<PAGE>

                                Transaction has been approved by a majority of
                                the members of the Board of Directors of the
                                Company having no personal stake in such
                                Affiliate Transaction (or, if there are no such
                                members, by all of the directors and by the
                                procedure described in clause (c) below); and

                        (c)     with respect to any Affiliate Transaction or
                                series of related Affiliate Transactions
                                involving aggregate consideration in excess of
                                $25.0 million, other than a Permitted
                                Investment, an opinion as to the fairness to the
                                Company of such Affiliate Transaction from a
                                financial point of view issued by an accounting,
                                appraisal or investment banking firm of national
                                standing.

        Notwithstanding the foregoing, the following items shall not be deemed
to be Affiliate Transactions and, therefore, shall not be subject to the
provisions of the prior paragraph:

                (1)     any employment agreement entered into with any executive
                        officer of the Company, any Sister Guarantor or any of
                        the Restricted Subsidiaries that is entered into by the
                        Company, any Sister Guarantor or any of the Restricted
                        Subsidiaries in the ordinary course of business and
                        substantially consistent with the compensation
                        arrangements of similarly situated executive officers at
                        comparable companies engaged in Permitted Businesses;

                (2)     transactions between or among the Company, the Sister
                        Guarantors and/or the Restricted Subsidiaries;

                (3)     transactions with a Person that is an Affiliate of the
                        Company or a Sister Guarantor or a Restricted Subsidiary
                        solely because the Company or a Sister Guarantor or a
                        Restricted Subsidiary owns an Equity Interest in, or
                        controls, such Person;

                (4)     payment of reasonable directors' fees to Persons in an
                        aggregate annual amount per Person that is substantially
                        consistent with directors' fees at comparable companies
                        engaged in Permitted Businesses;

                (5)     issuances or sales of Equity Interests (other than
                        Disqualified Stock) of the Company;

                (6)     transactions entered into in connection with the Escrow
                        Corp. Merger;

                (7)     payments to the Parent of customary tax sharing payments
                        (including, without limitation, pursuant to the Tax
                        Sharing Agreement) and of amounts necessary to pay
                        Parent's reasonable and customary administrative and
                        overhead expenses and reasonable transaction costs
                        related to financings;

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<PAGE>

                (8)     arrangements between some or all of the Company, the
                        Guarantors and the Restricted Subsidiaries, on the one
                        hand, and Verestar or its Subsidiaries, on the other
                        hand, in the ordinary course of business and in
                        existence on the Issue Date; and

                (9)     Restricted Payments that are permitted by Section 4.07
                        hereof and Permitted Investments.

        Section 4.12.   Liens.

        The Company and each Sister Guarantor shall not, and shall not permit
any of their respective Restricted Subsidiaries to, create, incur, assume or
otherwise cause or suffer to exist or become effective any Lien of any kind
securing Indebtedness, Attributable Debt or trade payables (other than Permitted
Liens) upon any of their property or assets, now owned or hereafter acquired,
unless all payments due under this Indenture and the Notes are secured on an
equal and ratable basis with the Obligations so secured until such time as such
Obligations are no longer secured by a Lien.

        Section 4.13.   Corporate Existence.

        Subject to Article 5 hereof, the Company shall do or cause to be done
all things necessary to preserve and keep in full force and effect:

                (1)     its corporate existence, and the corporate, partnership
                        or other existence of each of its Subsidiaries, in
                        accordance with the respective organizational documents
                        (as the same may be amended from time to time) of the
                        Company or any such Subsidiary and

                (2)     the rights (charter and statutory), licenses and
                        franchises of the Company and its Subsidiaries;

provided, however, that the Company shall not be required to preserve any such
right, license or franchise, or the corporate, partnership or other existence of
any of its Subsidiaries, if its Board of Directors shall determine that the
preservation thereof is no longer desirable in the conduct of the business of
the Company and its Subsidiaries, taken as a whole, and that the loss thereof is
not adverse in any material respect to the Holders of the Notes.

        Section 4.14.   Offer to Repurchase Upon Change of Control.

        If a Change of Control occurs, the Company shall make an offer (a
"Change of Control Offer") to each Holder to repurchase all or any part (equal
to $1,000 or an integral multiple thereof) of each Holder's Notes at a purchase
price, in cash, equal to 101% of the Accreted Value of the Notes on the date of
purchase plus Liquidated Damages, if any, on the Notes purchased, to the date of
purchase (a "Change of Control Payment"). Within 15 days following any Change of
Control, the Company shall mail a notice to each Holder describing the
transaction or transactions that constitute a Change of Control and stating:

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                (1)     that the Change of Control Offer is being made pursuant
                        to this Section 4.14 and that all Notes tendered will be
                        accepted for payment;

                (2)     the purchase price and the purchase date, which shall be
                        no earlier than 30 days and no later than 60 days from
                        the date such notice is mailed (the "Change of Control
                        Payment Date");

                (3)     that any Note not tendered will continue to accrete
                        interest;

                (4)     that the Accreted Value of all Notes accepted for
                        payment pursuant to the Change of Control Offer shall
                        cease to increase after the Change of Control Payment
                        Date;

                (5)     that Holders electing to have any Notes purchased
                        pursuant to a Change of Control Offer will be required
                        to surrender the Notes, with the form entitled "Option
                        of Holder to Elect Purchase" on the reverse of the Notes
                        completed, to the Paying Agent at the address specified
                        in the notice prior to the close of business on the
                        third Business Day preceding the Change of Control
                        Payment Date;

                (6)     that Holders will be entitled to withdraw their election
                        if the Paying Agent receives, not later than the close
                        of business on the second Business Day preceding the
                        Change of Control Payment Date, a telegram, telex,
                        facsimile transmission or letter setting forth the name
                        of the Holder, the principal amount at maturity of Notes
                        delivered for purchase, and a statement that such Holder
                        is withdrawing his election to have the Notes purchased;

                (7)     that Holders whose Notes are being purchased only in
                        part will be issued new Notes equal in principal amount
                        at maturity to the unpurchased portion of the Notes
                        surrendered, which unpurchased portion must be equal to
                        $1,000 in principal amount at maturity or an integral
                        multiple thereof; and

                (8)     that Holders electing to have a Note purchased pursuant
                        to a Change of Control Offer may elect to have Notes
                        purchased in integral multiples of $1,000 only.

        On the Change of Control Payment Date, the Company shall, to the extent
lawful,

                (1)     accept for payment all Notes or portions of Notes
                        properly tendered pursuant to the Change of Control
                        Offer;

                (2)     deposit with the Paying Agent an amount equal to the
                        Change of Control Payment in respect of all Notes or
                        portions of Notes properly tendered; and

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                (3)     deliver or cause to be delivered to the Trustee the
                        Notes so accepted together with an Officers' Certificate
                        stating the aggregate principal amount at maturity of
                        Notes or portions thereof being purchased by the
                        Company.

        The Paying Agent shall promptly mail to each Holder of Notes properly
tendered the Change of Control Payment for such Notes, and the Trustee shall
promptly authenticate and mail (or cause to be transferred by book entry) to
each Holder a new Note equal in principal amount at maturity to any unpurchased
portion of the Notes surrendered, if any; provided that each new Note shall be
in a principal amount at maturity of $1,000 or an integral multiple of $1,000.

        The Change of Control provisions described above shall be applicable
whether or not any other provisions of this Indenture are applicable. The
Company shall comply with the requirements of Section 14(e) of the Exchange Act
and any other securities laws or regulations to the extent those laws and
regulations are applicable to any Change of Control Offer. If the provisions of
any of the applicable securities laws or securities regulations conflict with
the provisions of this Section 4.14, the Company shall comply with the
applicable securities laws and regulations and shall not be deemed to have
breached its obligations under this Section 4.14 by virtue of the compliance.

        The Company shall not be required to make a Change of Control Offer upon
a Change of Control if a third party makes the Change of Control Offer in the
manner, at the times and otherwise in compliance with the requirements set forth
in this Section 4.14 and purchases all Notes properly tendered and not withdrawn
under the Change of Control Offer.

        Section 4.15.   Anti-Layering.

        The Company shall not incur, create, issue, assume, guarantee or
otherwise become liable for any Indebtedness that is subordinate or junior in
right of payment to any Senior Debt of the Company and senior in any respect in
right of payment to the Notes. No Group Guarantor shall incur, create, issue,
assume, guarantee or otherwise become liable for any Indebtedness that is
subordinate or junior in right of payment to the Senior Debt of such Group
Guarantor and senior in any respect in right of payment to such Group
Guarantor's Note Guarantee.

        Section 4.16.   Sale and Leaseback Transactions.

        The Company and each Sister Guarantor shall not, and shall not permit
any of their respective Restricted Subsidiaries to, enter into any sale and
leaseback transaction; provided that the Company, any Sister Guarantor or any
Restricted Subsidiary may enter into a sale and leaseback transaction if:

                (1)     the Company, such Sister Guarantor or such Restricted
                        Subsidiary, as applicable, could have (a) incurred
                        Indebtedness in an amount equal to the Attributable Debt
                        relating to such sale and leaseback transaction pursuant
                        to the provisions of Section 4.09 hereof and (b)
                        incurred a Lien to secure such Indebtedness pursuant to
                        the provisions of Section 4.12 hereof;

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                (2)     the gross cash proceeds of that sale and leaseback
                        transaction are at least equal to the fair market value,
                        as determined in good faith by the Board of Directors of
                        the Company and set forth in an Officers' Certificate
                        delivered to the Trustee, of the property that is the
                        subject of that sale and leaseback transaction; and

                (3)     the transfer of assets in that sale and leaseback
                        transaction is permitted by, and the Company applies the
                        proceeds of such transaction in compliance with, Section
                        4.10 hereof.

        Section 4.17.   Covenant Suspension.

        If on any date following the Issue Date:

                (a)     the Notes have an Investment Grade Rating and

                (b)     no Default or Event of Default has occurred and is
                        continuing under the Indenture,

then, beginning on that day the Company, the Sister Guarantors and the
Restricted Subsidiaries shall not be subject to the following Sections of this
Indenture: Section 3.09, Section 4.07, Section 4.08, Section 4.09, Section 4.10,
Section 4.11, Section 4.15, Section 4.19, clause (1)(a) of Section 4.16, the
proviso to the last paragraph of the definition of "Unrestricted Subsidiary" in
Section 1.01, and clause (4) of Section 5.01 (collectively, the "Suspended
Covenants"). In the event the foregoing Sections are suspended pursuant to this
Section 4.17 and the rating assigned by both Rating Agencies should subsequently
decline to below an Investment Grade Rating, the foregoing Sections shall be
reinstituted as of and from the date of such rating decline. Compliance with
Section 4.07 hereof shall be calculated as if it had been in effect since the
Issue Date except that no Default shall be deemed to have occurred solely by
reason of a Restricted Payment made while that Section was suspended, and no
other Default shall be deemed to have occurred with respect to the suspended
Sections during the time they were suspended (or after that time based solely on
events that occurred during that time).

        Section 4.18.   Additional Subsidiary Note Guarantees.

        The Company and each Sister Guarantor shall cause any Person that shall
become a Wholly Owned Domestic Restricted Subsidiary of the Company or the
Sister Guarantor, as the case may be, after the consummation of the Escrow Corp.
Merger to become a Guarantor and evidence its Note Guarantee by executing a
supplemental indenture in the form of supplemental indenture attached as Exhibit
B and deliver an Opinion of Counsel to the Trustee within ten Business Days of
the date on which it was acquired and created to the effect that such
supplemental indenture has been duly authorized, executed and delivered by that
Wholly Owned Domestic Restricted Subsidiary, and is enforceable in accordance
with its terms (subject to customary exceptions); provided that this Section
4.18 does not apply to any Subsidiaries of the Company or any Group Guarantor
that have properly been designated as Unrestricted

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Subsidiaries in accordance with this Indenture for so long as they continue to
constitute Unrestricted Subsidiaries.

        Section 4.19.   Designation of Restricted and Unrestricted Subsidiaries.

                The Board of Directors of the Company may designate any
Restricted Subsidiary of the Company or of a Sister Guarantor to be an
Unrestricted Subsidiary if that designation would not cause a Default. If a
Restricted Subsidiary is designated as an Unrestricted Subsidiary, the aggregate
fair market value of all outstanding Investments owned by the Company, the
Sister Guarantors and the Restricted Subsidiaries in the Subsidiary properly
designated shall be deemed to be an Investment made as of the time of the
designation and shall reduce the amount available for Restricted Payments under
Section 4.07 hereof or Permitted Investments, as determined by the Company. That
designation shall only be permitted if the Investment would be permitted at that
time and if the Restricted Subsidiary otherwise meets the definition of an
Unrestricted Subsidiary. The Board of Directors of the Company or a Sister
Guarantor may redesignate any Unrestricted Subsidiary to be a Restricted
Subsidiary as provided in the last paragraph of the definition thereof.

                                    ARTICLE 5

                                   SUCCESSORS

        Section 5.01.   Merger, Consolidation, or Sale of Assets.

        The Company shall not, directly or indirectly: (1) consolidate or merge
with or into another Person (whether or not the Company is the surviving
corporation); or (2) sell, assign, transfer, convey or otherwise dispose of all
or substantially all of the properties or assets of the Company and its
Restricted Subsidiaries taken as a whole, in one or more related transactions,
to another Person, unless:

                (1)     either: (a) the Company is the surviving corporation; or
                        (b) the Person formed by or surviving any such
                        consolidation or merger (if other than the Company) or
                        to which such sale, assignment, transfer, conveyance or
                        other disposition has been made is a corporation
                        organized or existing under the laws of the United
                        States, any state of the United States or the District
                        of Columbia;

                (2)     the Person formed by or surviving any such consolidation
                        or merger (if other than the Company) or the Person to
                        which such sale, assignment, transfer, conveyance or
                        other disposition has been made assumes all the
                        Obligations of the Company under the Notes, this
                        Indenture and the Registration Rights Agreement pursuant
                        to agreements reasonably satisfactory to the Trustee;

                (3)     immediately after such transaction, no Default or Event
                        of Default exists; and

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                (4)     except in the case of (A) a merger of the Company with
                        or into a Wholly Owned Restricted Subsidiary of the
                        Company, a Sister Guarantor or a Wholly Owned Restricted
                        Subsidiary of a Sister Guarantor, (B) a merger entered
                        into solely for the purpose of reincorporating the
                        Company in another jurisdiction and (C) the Escrow Corp.
                        Merger:

                        (x) in the case of a merger or consolidation in which
                        the Company is the surviving corporation, the Parent, at
                        the time of the transaction, after giving pro forma
                        effect to the transaction as of such date for balance
                        sheet purposes and as if the transaction had occurred at
                        the beginning of the most recently ended four full
                        fiscal quarter period of the Company for which internal
                        financial statements are available for income statement
                        purposes, (i) would have had a Debt to Adjusted
                        Consolidated Cash Flow Ratio no greater than 7.5 to 1.0
                        or (ii) would have had a Debt to Adjusted Consolidated
                        Cash Flow Ratio that was not greater than its Debt to
                        Adjusted Consolidated Cash Flow Ratio for the same
                        period without giving pro forma effect to such
                        transaction, or

                        (y) in the case of any other such transaction, the
                        entity or Person formed by or surviving any such
                        consolidation or merger (if other than the Company), or
                        to which the sale, assignment, transfer, conveyance or
                        other disposition shall have been made, at the time of
                        the transaction, after giving pro forma effect to the
                        transaction as of such date for balance sheet purposes
                        and as if such transaction had occurred at the beginning
                        of the most recently ended four full fiscal quarter
                        period of such entity or Person for which internal
                        financial statements are available for income statement
                        purposes, (i) would have had a Debt to Adjusted
                        Consolidated Cash Flow Ratio no greater than 7.5 to 1.0
                        or (ii) would have had a Debt to Adjusted Consolidated
                        Cash Flow Ratio that was not greater than the Debt to
                        Adjusted Consolidated Cash Flow Ratio of the Parent for
                        the same period without giving pro forma effect to such
                        transaction.

        In addition, the Company shall not, directly or indirectly, lease all or
substantially all of its properties or assets, in one or more related
transactions, to any other Person. This Section 5.01 not apply to a sale,
assignment, transfer, conveyance or other disposition of assets between or among
the Company and any of the Guarantors.

        Section 5.02.   Successor Corporation Substituted.

        Upon any consolidation or merger, or any sale, assignment, transfer,
conveyance or other disposition of all or substantially all of the assets of the
Company in accordance with Section 5.01 hereof, the successor corporation formed
by such consolidation or into or with which the Company is merged or to which
such sale, assignment, transfer, conveyance or other disposition is made shall
succeed to, and be substituted for (so that from and after the date of such
consolidation, merger, sale, conveyance or other disposition, the provisions of
this Indenture

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referring to the "Company" shall refer instead to the successor corporation and
not to the Company), and may exercise every right and power of the Company under
this Indenture with the same effect as if such successor Person had been named
as the Company herein; provided, however, that the predecessor Company shall not
be relieved from the obligation to pay the Accreted Value of the Notes except in
the case of a sale of all of the Company's assets that meets the requirements of
Section 5.01 hereof.

                                    ARTICLE 6

                              DEFAULTS AND REMEDIES

        Section 6.01.   Events of Default.

        Each of the following constitutes an Event of Default:

                (1)     default for 30 days in the payment when due of
                        Liquidated Damages with respect to, the Notes whether or
                        not prohibited by the subordination provisions of
                        Article 11 hereof;

                (2)     default in payment when due of the Accreted Value of, or
                        premium, if any, on the Notes, whether or not prohibited
                        by the subordination provisions of Article 11 hereof;

                (3)     failure by the Company to comply with the provisions of
                        Article 5 hereof or failure by the Company to consummate
                        a Change of Control Offer or Asset Sale Offer in
                        accordance with the provisions of this Indenture;

                (4)     failure by the Company or any of the Sister Guarantors
                        for 30 days after notice to comply with any of the other
                        agreements in this Indenture or the Notes;

                (5)     default under any mortgage, indenture or instrument
                        under which there may be issued or by which there may be
                        secured or evidenced any Indebtedness for money borrowed
                        by the Company or any of its Significant Subsidiaries
                        (or the payment of which is guaranteed by the Company or
                        any of its Significant Subsidiaries) whether such
                        Indebtedness or Guarantee now exists, or is created
                        after the Issue Date, if that default:

                        (a)     is caused by a failure to pay principal of, or
                                interest or premium, if any, on such
                                Indebtedness prior to the expiration of the
                                grace period provided in such Indebtedness on
                                the date of such default (a "Payment Default");
                                or

                        (b)     results in the acceleration of such Indebtedness
                                prior to its express maturity,

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                        and, in each case referred to in clauses (a) and (b)
                        above, the principal amount of any such Indebtedness,
                        together with the principal amount of any other such
                        Indebtedness under which there has been a Payment
                        Default or the maturity of which has been so
                        accelerated, aggregates $20.0 million or more;

                (6)     failure by the Company or any of its Significant
                        Subsidiaries to pay final judgments aggregating in
                        excess of $20.0 million, which judgments are not paid,
                        discharged or stayed for a period of 60 days;

                (7)     except as permitted by this Indenture, any Note
                        Guarantee by any Significant Subsidiary of the Company
                        shall be held in final and non-appealable judgment to be
                        unenforceable or invalid or shall cease for any reason
                        to be in full force and effect or any such Guarantor
                        that is a Significant Subsidiary of the Company, or any
                        Person acting on behalf of any such Guarantor, shall in
                        writing deny or disaffirm its obligations under its Note
                        Guarantee;

                (8)     failure by the Company to effect the mandatory
                        redemption of the Notes as provided for in Section 3.08
                        hereof, and

                (9)     the Company or any of its Significant Subsidiaries
                        pursuant to or within the meaning of Bankruptcy Law:

                        (a)     commences a voluntary case,

                        (b)     consents to the entry of an order for relief
                                against it in an involuntary case,

                        (c)     consents to the appointment of a custodian of it
                                or for all or substantially all of its property,

                        (d)     makes a general assignment for the benefit of
                                its creditors, or

                        (e)     generally is not paying its debts as they become
                                due; or

                (10)    a court of competent jurisdiction enters an order or
                        decree under any Bankruptcy Law that:

                        (a)     is for relief against the Company or any of its
                                Significant Subsidiaries in an involuntary case;

                        (b)     appoints a custodian of the Company or any of
                                its Significant Subsidiaries or for all or
                                substantially all of the property of the Company
                                or any of its Significant Subsidiaries; or

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                        (c)     orders the liquidation of the Company or any of
                                its Significant Subsidiaries;

                        and the order or decree remains unstayed and in effect
                        for 60 consecutive days.

        Section 6.02.   Acceleration.

        In the case of an Event of Default specified in clause (9) or (10) of
Section 6.01 hereof, with respect to the Company or any Restricted Subsidiary
that is a Significant Subsidiary, all outstanding Notes shall become due and
payable immediately in an amount equal to the Accreted Value of the Notes
outstanding on the date of acceleration, without further action or notice.

        If any other Event of Default occurs and is continuing, the Trustee or
the Holders of at least 25% in aggregate principal at maturity of the then
outstanding Notes may declare all the Notes to be due and payable immediately in
an amount equal to the Accreted Value of the Notes outstanding on the date of
acceleration. Upon any such declaration, the Accreted Value of the Notes
outstanding on the date of acceleration shall become immediately due and
payable.

        Section 6.03.   Other Remedies.

        If an Event of Default occurs and is continuing, the Trustee may pursue
any available remedy to collect the payment of Accreted Value of, Liquidated
Damages and premium, if any, on the Notes or to enforce the performance of any
provision of the Notes or this Indenture.

        The Trustee may maintain a proceeding even if it does not possess any of
the Notes or does not produce any of them in the proceeding. A delay or omission
by the Trustee or any Holder of a Note in exercising any right or remedy
accruing upon an Event of Default shall not impair the right or remedy or
constitute a waiver of or acquiescence in the Event of Default. All remedies are
cumulative to the extent permitted by law.

        Section 6.04.   Waiver of Past Defaults.

        Holders of not less than a majority in aggregate principal amount at
maturity of the then outstanding Notes by notice to the Trustee may on behalf of
the Holders of all of the Notes waive an existing Default or Event of Default
and its consequences hereunder, except a continuing Default or Event of Default
in the payment of the Accreted Value of, and Liquidated Damages and premium, if
any, on the Notes (including in connection with an offer to purchase) (provided,
however, that the Holders of a majority in aggregate principal amount at
maturity of the then outstanding Notes may rescind an acceleration and its
consequences, including any related payment default that resulted from such
acceleration). Upon any such waiver, such Default shall cease to exist, and any
Event of Default arising therefrom shall be deemed to have been cured for every
purpose of this Indenture, but no such waiver shall extend to any subsequent or
other Default or impair any right consequent thereon.

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        Section 6.05.   Control by Majority.

        Holders of a majority in principal amount at maturity of the then
outstanding Notes may direct the time, method and place of conducting any
proceeding for exercising any remedy available to the Trustee or exercising any
trust or power conferred on it. However, the Trustee may refuse to follow any
direction that conflicts with law or this Indenture that the Trustee determines
may be unduly prejudicial to the rights of other Holders of Notes or that may
involve the Trustee in personal liability.

        Section 6.06.   Limitation on Suits.

        A Holder of a Note may pursue a remedy with respect to this Indenture or
the Notes only if:

                (1)     the Holder of a Note gives to the Trustee written notice
                        of a continuing Event of Default;

                (2)     the Holders of at least 25% in principal amount at
                        maturity of the then outstanding Notes make a written
                        request to the Trustee to pursue the remedy;

                (3)     such Holder of a Note or Holders of Notes offer and, if
                        requested, provide to the Trustee indemnity satisfactory
                        to the Trustee against any loss, liability or expense;

                (4)     the Trustee does not comply with the request within 60
                        days after receipt of the request and the offer and, if
                        requested, the provision of indemnity; and

                (5)     during such 60-day period the Holders of a majority in
                        principal amount at maturity of the then outstanding
                        Notes do not give the Trustee a direction inconsistent
                        with the request.

        A Holder of a Note may not use this Indenture to prejudice the rights of
another Holder of a Note or to obtain a preference or priority over another
Holder of a Note.

        Section 6.07.   Rights of Holders of Notes to Receive Payment.

        Notwithstanding any other provision of this Indenture, the right of any
Holder of a Note to receive payment of Accreted Value, Liquidated Damages and
premium, if any, on the Note, on or after the respective due dates expressed in
the Note (including in connection with an offer to purchase), or to bring suit
for the enforcement of any such payment on or after such respective dates, shall
not be impaired or affected without the consent of such Holder.

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        Section 6.08.   Collection Suit by Trustee.

        If an Event of Default specified in clauses (1) or (2) of Section 6.01
occurs and is continuing, the Trustee is authorized to recover judgment in its
own name and as trustee of an express trust against the Company for the whole
amount of Accreted Value, Liquidated Damages and premium, if any, remaining
unpaid on the Notes and interest on overdue Accreted Value, to the extent
lawful, and such further amount as shall be sufficient to cover the costs and
expenses of collection, including the reasonable compensation, expenses,
disbursements and advances of the Trustee, its agents and counsel.

        Section 6.09.   Trustee May File Proofs of Claim.

        The Trustee is authorized to file such proofs of claim and other papers
or documents as may be necessary or advisable in order to have the claims of the
Trustee (including any claim for the reasonable compensation, expenses,
disbursements and advances of the Trustee, its agents and counsel) and the
Holders of the Notes allowed in any judicial proceedings relative to the Company
(or any other obligor upon the Notes), its creditors or its property and shall
be entitled and empowered to collect, receive and distribute any money or other
property payable or deliverable on any such claims and any custodian in any such
judicial proceeding is hereby authorized by each Holder to make such payments to
the Trustee, and in the event that the Trustee shall consent to the making of
such payments directly to the Holders, to pay to the Trustee any amount due to
it for the reasonable compensation, expenses, disbursements and advances of the
Trustee, its agents and counsel, and any other amounts due the Trustee under
Section 7.07 hereof. To the extent that the payment of any such compensation,
expenses, disbursements and advances of the Trustee, its agents and counsel, and
any other amounts due the Trustee under Section 7.07 hereof out of the estate in
any such proceeding, shall be denied for any reason, payment of the same shall
be secured by a Lien on, and shall be paid out of, any and all distributions,
dividends, money, securities and other properties that the Holders may be
entitled to receive in such proceeding whether in liquidation or under any plan
of reorganization or arrangement or otherwise. Nothing herein contained shall be
deemed to authorize the Trustee to authorize or consent to or accept or adopt on
behalf of any Holder any plan of reorganization, arrangement, adjustment or
composition affecting the Notes or the rights of any Holder, or to authorize the
Trustee to vote in respect of the claim of any Holder in any such proceeding.

        Section 6.10.   Priorities.

        If the Trustee collects any money pursuant to this Article, it shall pay
out the money in the following order:

        First: to the Trustee, its agents and attorneys for amounts due under
        Section 7.07 hereof, including payment of all compensation, expense and
        liabilities incurred, and all advances made, by the Trustee and the
        costs and expenses of collection;

        Second: to Holders of Notes for amounts due and unpaid on the Notes for
        Accreted Value, Liquidated Damages and premium, if any, ratably, without
        preference or priority

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        of any kind, according to the amounts due and payable on the Notes for
        Accreted Value, Liquidated Damages and premium, if any, respectively;
        and

        Third: to the Company or to such party as a court of competent
        jurisdiction shall direct.

        The Trustee may fix a record date and payment date for any payment to
Holders of Notes pursuant to this Section 6.10.

        Section 6.11.   Undertaking for Costs.

        In any suit for the enforcement of any right or remedy under this
Indenture or in any suit against the Trustee for any action taken or omitted by
it as a Trustee, a court in its discretion may require the filing by any party
litigant in the suit of an undertaking to pay the costs of the suit, and the
court in its discretion may assess reasonable costs, including reasonable
attorneys' fees and expenses, against any party litigant in the suit, having due
regard to the merits and good faith of the claims or defenses made by the party
litigant. This Section does not apply to a suit by the Trustee, a suit by a
Holder of a Note pursuant to Section 6.07 hereof, or a suit by Holders of more
than 10% in principal amount at maturity of the then outstanding Notes.

                                    ARTICLE 7

                                     TRUSTEE

        Section 7.01.   Duties of Trustee.

        (a)     If an Event of Default has occurred and is continuing, the
Trustee shall exercise such of the rights and powers vested in it by this
Indenture, and use the same degree of care and skill in its exercise, as a
prudent person would exercise or use under the circumstances in the conduct of
such person's own affairs.

        (b)     Except during the continuance of an Event of Default:

                (i)     the duties of the Trustee shall be determined solely by
                        the express provisions of this Indenture and the Trustee
                        need perform only those duties that are specifically set
                        forth in this Indenture and no others, and no implied
                        covenants or obligations shall be read into this
                        Indenture against the Trustee; and

                (ii)    in the absence of bad faith on its part, the Trustee may
                        conclusively rely, as to the truth of the statements and
                        the correctness of the opinions expressed therein, upon
                        certificates or opinions furnished to the Trustee and
                        conforming to the requirements of this Indenture.
                        However, the Trustee shall examine the certificates and
                        opinions required to be furnished to the Trustee
                        hereunder to determine whether or not they conform to
                        the requirements of this Indenture.

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        (c)     The Trustee may not be relieved from liabilities for its own
negligent action, its own negligent failure to act, or its own willful
misconduct, except that:

                (i)     this paragraph does not limit the effect of paragraph
                        (b) of this Section 7.01;

                (ii)    the Trustee shall not be liable for any error of
                        judgment made in good faith by a Responsible Officer,
                        unless it is proved that the Trustee was negligent in
                        ascertaining the pertinent facts; and

                (iii)   the Trustee shall not be liable with respect to any
                        action it takes or omits to take in good faith in
                        accordance with a direction received by it pursuant to
                        Section 6.05 hereof.

        (d)     Whether or not therein expressly so provided, every provision of
this Indenture that in any way relates to the Trustee is subject to paragraphs
(a), (b), and (c) of this Section 7.01.

        (e)     No provision of this Indenture shall require the Trustee to
expend or risk its own funds or incur any liability. The Trustee shall be under
no obligation to exercise any of its rights and powers under this Indenture at
the request of any Holders, unless such Holder shall have offered to the Trustee
security and indemnity satisfactory to it against any loss, liability or
expense.

        (f)     The Trustee shall not be liable for interest on any money
received by it except as the Trustee may agree in writing with the Company.
Money held in trust by the Trustee need not be segregated from other funds
except to the extent required by law.

        Section 7.02.   Rights of Trustee.

        (a)     The Trustee may conclusively rely upon any document (whether in
its original or facsimile form) believed by it to be genuine and to have been
signed or presented by the proper Person. The Trustee need not investigate any
fact or matter stated in the document.

        (b)     Before the Trustee acts or refrains from acting, it may require
an Officers' Certificate or an Opinion of Counsel or both. The Trustee shall not
be liable for any action it takes or omits to take in good faith in reliance on
such Officers' Certificate or Opinion of Counsel. The Trustee may consult with
counsel of its own selection and the written and oral advice of such counsel or
any Opinion of Counsel shall be full and complete authorization and protection
from liability in respect of any action taken, suffered or omitted by it
hereunder in good faith and in reliance thereon.

        (c)     The Trustee may act through its attorneys and agents and shall
not be responsible for the misconduct or negligence of any agent appointed with
due care.

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        (d)     The Trustee shall not be liable for any action it takes or omits
to take in good faith that it believes to be authorized or within the rights or
powers conferred upon it by this Indenture.

        (e)     Unless otherwise specifically provided in this Indenture, any
demand, request, direction or notice from the Company shall be sufficient if
signed by an Officer of the Company.

        (f)     The Trustee shall be under no obligation to exercise any of the
rights or powers vested in it by this Indenture at the request or direction of
any of the Holders unless such Holders shall have offered to the Trustee
reasonable security or indemnity against the costs, expenses and liabilities
that might be incurred by it in compliance with such request or direction.

        Section 7.03.   Individual Rights of Trustee.

        The Trustee in its individual or any other capacity may become the owner
or pledgee of Notes and may otherwise deal with the Company or any Affiliate of
the Company with the same rights it would have if it were not Trustee. However,
in the event that the Trustee acquires any conflicting interest it must
eliminate such conflict within 90 days, apply to the SEC for permission to
continue as trustee or resign. Any Agent may do the same with like rights and
duties. The Trustee is also subject to Sections 7.10 and 7.11 hereof.

        Section 7.04.   Trustee's Disclaimer.

        The Trustee shall not be responsible for and makes no representation as
to the validity or adequacy of this Indenture or the Notes, it shall not be
accountable for the Company's use of the proceeds from the Notes or any money
paid to the Company or upon the Company's direction under any provision of this
Indenture, it shall not be responsible for the use or application of any money
received by any Paying Agent other than the Trustee, and it shall not be
responsible for any statement or recital herein or any statement in the Notes or
any other document in connection with the sale of the Notes or pursuant to this
Indenture other than its certificate of authentication.

        Section 7.05.   Notice of Defaults.

        If a Default or Event of Default occurs and is continuing and if it is
actually known to a Responsible Officer of the Trustee, the Trustee shall mail
to Holders of Notes a notice of the Default or Event of Default within 90 days
after it occurs. Except a Default or Event of Default relating to the payment of
Accreted Value of, or Liquidated Damages on, the Notes, the Trustee may withhold
the notice if and so long as a committee of its Responsible Officers in good
faith determines that withholding the notice is in the interests of the Holders
of the Notes.

        Section 7.06.   Reports by Trustee to Holders of the Notes.

        Within 60 days after each May 15 beginning with the May 15 following the
Issue Date, and for so long as Notes remain outstanding, the Trustee shall mail
to the Holders of the Notes a brief report dated as of such reporting date that
complies with TIA Section 313(a) (but if no event described in TIA Section
313(a) has occurred within the twelve months preceding the reporting date,

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no report need be transmitted). The Trustee also shall comply with TIA Section
313(b). The Trustee shall also transmit by mail all reports as required by TIA
Section 313(c).

        A copy of each report at the time of its mailing to the Holders of Notes
shall be mailed to the Company and filed with the SEC and each stock exchange on
which the Notes are listed in accordance with TIA Section 313(d). The Company
shall promptly notify the Trustee when the Notes are listed on any stock
exchange or delisted therefrom.

        Section 7.07.   Compensation and Indemnity.

        The Company shall pay to the Trustee from time to time reasonable
compensation for its acceptance of this Indenture and services hereunder. The
Trustee's compensation shall not be limited by any law on compensation of a
trustee of an express trust. The Company shall reimburse the Trustee promptly
upon request for all reasonable disbursements, advances and expenses incurred or
made by it in addition to the compensation for its services. Such expenses shall
include the reasonable compensation, disbursements and expenses of the Trustee's
agents and counsel.

        The Company shall fully indemnify the Trustee against any and all
losses, liabilities, claims, damages or expenses (including legal fees and
expenses) incurred by it arising out of or in connection with the acceptance or
administration of its duties under this Indenture, including the costs and
expenses of enforcing this Indenture against the Company (including this Section
7.07) and defending itself against any claim (whether asserted by the Company or
any Holder or any other person) or liability in connection with the exercise or
performance of any of its powers or duties hereunder, except to the extent any
such loss, liability or expense is caused by its own negligence or willful
misconduct. The Trustee shall notify the Company promptly of any claim for which
it may seek indemnity. Failure by the Trustee to so notify the Company shall not
relieve the Company of its obligations hereunder. The Company shall defend the
claim and the Trustee shall cooperate in the defense. The Trustee may have
separate counsel and the Company shall pay the reasonable fees and expenses of
such counsel. The Company need not pay for any settlement made without its
consent, which consent shall not be unreasonably withheld.

        The obligations of the Company under this Section 7.07 shall survive the
satisfaction and discharge of this Indenture and the resignation or removal of
the Trustee.

        To secure the Company's payment obligations in this Section 7.07, the
Trustee shall have a Lien prior to the Notes on all money or property held or
collected by the Trustee, except that held in trust to pay Accreted Value on
particular Notes. Such Lien shall survive the satisfaction and discharge of this
Indenture.

        When the Trustee incurs expenses or renders services after an Event of
Default specified in clauses (9) or (10) of Section 6.01 hereof occurs, the
expenses and the compensation for the services (including the fees and expenses
of its agents and counsel) are intended to constitute expenses of administration
under any Bankruptcy Law.

        The Trustee shall comply with the provisions of TIA Section 313(b)(2) to
the extent applicable.

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        Section 7.08.   Replacement of Trustee.

        A resignation or removal of the Trustee and appointment of a successor
Trustee shall become effective only upon the successor Trustee's acceptance of
appointment as provided in this Section.

        The Trustee may resign in writing at any time and be discharged from the
trust hereby created by so notifying the Company. The Holders of a majority in
principal amount at maturity of the then outstanding Notes may remove the
Trustee by so notifying the Trustee and the Company in writing. The Company may
remove the Trustee if:

                (a)     the Trustee fails to comply with Section 7.10 hereof;

                (b)     the Trustee is adjudged a bankrupt or an insolvent or an
                        order for relief is entered with respect to the Trustee
                        under any Bankruptcy Law;

                (c)     a custodian or public officer takes charge of the
                        Trustee or its property; or

                (d)     the Trustee becomes incapable of acting.

        If the Trustee resigns or is removed or if a vacancy exists in the
office of Trustee for any reason, the Company shall promptly appoint a successor
Trustee. Within one year after the successor Trustee takes office, the Holders
of a majority in principal amount at maturity of the then outstanding Notes may
appoint a successor Trustee to replace the successor Trustee appointed by the
Company.

        If a successor Trustee does not take office within 60 days after the
retiring Trustee resigns or is removed, the retiring Trustee, the Company, or
the Holders of at least 10% in principal amount at maturity of the then
outstanding Notes may petition at the expense of the Company any court of
competent jurisdiction for the appointment of a successor Trustee.

        If the Trustee, after written request by any Holder who has been a
Holder for at least six months, fails to comply with Section 7.10, such Holder
may petition any court of competent jurisdiction for the removal of the Trustee
and the appointment of a successor Trustee.

        A successor Trustee shall deliver a written acceptance of its
appointment to the retiring Trustee and to the Company. Thereupon, the
resignation or removal of the retiring Trustee shall become effective, and the
successor Trustee shall have all the rights, powers and duties of the Trustee
under this Indenture. The successor Trustee shall mail a notice of its
succession to Holders. The retiring Trustee shall promptly transfer all property
held by it as Trustee to the successor Trustee, provided all sums owing to the
Trustee hereunder have been paid and subject to the Lien provided for in Section
7.07 hereof.

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        Section 7.09.   Successor Trustee by Merger, etc.

        If the Trustee consolidates, merges or converts into, or transfers all
or substantially all of its corporate trust business to, another corporation,
the successor corporation without any further act shall be the successor
Trustee.

        Section 7.10.   Eligibility; Disqualification.

        There shall at all times be a Trustee hereunder that is a corporation
organized and doing business under the laws of the United States of America or
of any state thereof that is authorized under such laws to exercise corporate
trustee power, that is subject to supervision or examination by federal or state
authorities and that has a combined capital and surplus of at least $75.0
million as set forth in its most recent published annual report of condition.

        This Indenture shall always have a Trustee who satisfies the
requirements of TIA Section 310(a)(1), (2) and (5). The Trustee is subject to
TIA Section 310(b).

        Section 7.11.   Preferential Collection of Claims Against Company.

        The Trustee is subject to TIA Section 311(a), excluding any creditor
relationship listed in TIA Section 311(b). A Trustee who has resigned or been
removed shall be subject to TIA Section 311(a) to the extent indicated therein.

        Section 7.12.   Trustee's Application for Instructions from the Company.

        Any application by the Trustee for written instructions from the Company
may, at the option of the Trustee, set forth in writing any action proposed to
be taken or omitted by the Trustee under this Indenture and the date on and/or
after which such action shall be taken or such omission shall be effective. The
Trustee shall not be liable for any action taken by, or omission of, the Trustee
in accordance with a proposal included in such application on or after the date
specified in such application (which date shall not be less than three Business
Days after the date any officer of the Company actually receives such
application, unless any such officer shall have consented in writing to any
earlier date) unless prior to taking any such action (or the effective date in
the case of an omission), the Trustee shall have received written instructions
in response to such application specifying the action to be taken or omitted.

                                    ARTICLE 8

                    LEGAL DEFEASANCE AND COVENANT DEFEASANCE

        Section 8.01.   Option to Effect Legal Defeasance or Covenant
Defeasance.

        The Company may, at the option of its Board of Directors evidenced by a
resolution set forth in an Officers' Certificate, at any time, elect to have
either Section 8.02 or 8.03 hereof be applied to all outstanding Notes upon
compliance with the conditions set forth below in this Article 8.

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        Section 8.02.   Legal Defeasance and Discharge.

        Upon the Company's exercise under Section 8.01 hereof of the option
applicable to this Section 8.02, the Company and each of the Guarantors shall,
subject to the satisfaction of the conditions set forth in Section 8.04 hereof,
be deemed to have been discharged from their obligations with respect to all
outstanding Notes (including the Note Guarantees) on the date the conditions set
forth below are satisfied (hereinafter, "Legal Defeasance"). For this purpose,
Legal Defeasance means that the Company and the Guarantors shall be deemed to
have paid and discharged the entire Indebtedness represented by the outstanding
Notes (including the Note Guarantees), which shall thereafter be deemed to be
"outstanding" only for the purposes of Section 8.05 hereof and the other
Sections of this Indenture referred to in (1) and (2) below, and to have
satisfied all their other obligations under such Notes, the Note Guarantees and
this Indenture (and the Trustee, on demand of and at the expense of the Company,
shall execute proper instruments provided to it acknowledging the same), except
for the following provisions which shall survive until otherwise terminated or
discharged hereunder:

                (1)     the rights of Holders of outstanding Notes to receive
                        payments in respect of the Accreted Value of, or premium
                        and Liquidated Damages, if any, on such Notes when such
                        payments are due from the trust referred to in Section
                        8.04 hereof;

                (2)     the Company's obligations with respect to such Notes
                        under Article 2 and Section 4.02 hereof;

                (3)     the rights, powers, trusts, duties and immunities of the
                        Trustee, and the Company's and the Guarantor's
                        obligations in connection therewith; and

                (4)     this Article 8.

        Subject to compliance with this Article 8, the Company may exercise its
option under this Section 8.02 notwithstanding the prior exercise of its option
under Section 8.03 hereof.

        Section 8.03.   Covenant Defeasance.

        Upon the Company's exercise under Section 8.01 hereof of the option
applicable to this Section 8.03, the Company and the Group Guarantors shall,
subject to the satisfaction of the conditions set forth in Section 8.04 hereof,
be released from their obligations under the covenants contained in Sections
3.09, 4.07, 4.08, 4.09, 4.10, 4.11, 4.12, 4.14, 4.15, 4.16, 4.17, 4.18 and 4.19
hereof and clause 4 of Section 5.01 hereof with respect to the outstanding Notes
on and after the date the conditions set forth in Section 8.04 are satisfied
(hereinafter, "Covenant Defeasance"), and the Notes shall thereafter be deemed
not "outstanding" for the purposes of any direction, waiver, consent or
declaration or act of Holders (and the consequences of any thereof) in
connection with such covenants, but shall continue to be deemed "outstanding"
for all other purposes hereunder (it being understood that such Notes shall not
be deemed outstanding for accounting purposes). For this purpose, Covenant
Defeasance means that, with respect to the outstanding Notes and Note
Guarantees, the Company and the Guarantors may omit to comply

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with and shall have no liability in respect of any term, condition or limitation
set forth in any such covenant, whether directly or indirectly, by reason of any
reference elsewhere herein to any such covenant or by reason of any reference in
any such covenant to any other provision herein or in any other document and
such omission to comply shall not constitute a Default or an Event of Default
under Section 6.01 hereof, but, except as specified above, the remainder of this
Indenture and such Notes and Note Guarantees shall be unaffected thereby. In
addition, upon the Company's exercise under Section 8.01 hereof of the option
applicable to this Section 8.03 hereof, subject to the satisfaction of the
conditions set forth in Section 8.04 hereof, clauses (3) through (8) of Sections
6.01 hereof shall not constitute Events of Default.

        Section 8.04.   Conditions to Legal or Covenant Defeasance.

        The following shall be the conditions to the application of either
Section 8.02 or 8.03 hereof to the outstanding Notes:

        In order to exercise either Legal Defeasance or Covenant Defeasance:

                (1)     the Company must irrevocably deposit with the Trustee,
                        in trust, for the benefit of the Holders of the Notes,
                        cash in United States dollars, non-callable Government
                        Securities, or a combination thereof, in such amounts as
                        will be sufficient, in the opinion of a nationally
                        recognized firm of independent public accountants, to
                        pay the Accreted Value of, Liquidated Damages or
                        premium, if any, on the outstanding Notes on the stated
                        date for payment thereof or on the applicable redemption
                        date, as the case may be, and the Company shall specify
                        whether the Notes are being defeased to maturity or to a
                        particular redemption date;

                (2)     in the case of an election under Section 8.02 hereof,
                        the Company has delivered to the Trustee an Opinion of
                        Counsel reasonably acceptable to the Trustee confirming
                        that (a) the Company has received from, or there has
                        been published by, the Internal Revenue Service a ruling
                        or (b) since the Issue Date, there has been a change in
                        the applicable federal income tax law, in either case to
                        the effect that, and based thereon such Opinion of
                        Counsel shall confirm that, the Holders of the
                        outstanding Notes will not recognize income, gain or
                        loss for federal income tax purposes as a result of such
                        Legal Defeasance and will be subject to federal income
                        tax on the same amounts, in the same manner and at the
                        same times as would have been the case if such Legal
                        Defeasance had not occurred;

                (3)     in the case of an election under Section 8.03 hereof,
                        the Company shall have delivered to the Trustee an
                        Opinion of Counsel reasonably acceptable to the Trustee
                        confirming that the Holders of the outstanding Notes
                        will not recognize income, gain or loss for federal
                        income tax purposes as a result of such Covenant
                        Defeasance and will be subject to federal income tax on
                        the same amounts, in the same manner and at the same
                        times as would have been the case if such Covenant
                        Defeasance had not occurred;

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                (4)     no Default or Event of Default shall have occurred and
                        be continuing on the date of such deposit (other than a
                        Default or Event of Default resulting from the borrowing
                        of funds to be applied to such deposit)

                (5)     such Legal Defeasance or Covenant Defeasance shall not
                        result in a breach or violation of, or constitute a
                        default under any material agreement or instrument
                        (other than this Indenture) to which the Company, any
                        Sister Guarantor or any of the Restricted Subsidiaries
                        is a party or by which the Company, any Sister Guarantor
                        or any of the Restricted Subsidiaries is bound;

                (6)     the Company shall have delivered to the Trustee an
                        Opinion of Counsel to the effect that on the 91st day
                        following the deposit, the trust funds will not be
                        subject to the effect of any applicable bankruptcy,
                        insolvency, reorganization or similar laws affecting
                        creditors' rights generally;

                (7)     the Company shall have delivered to the Trustee an
                        Officers' Certificate stating that the deposit was not
                        made by the Company with the intent of preferring the
                        Holders over the other creditors of the Company with the
                        intent of defeating, hindering, delaying or defrauding
                        any other creditors of the Company or others; and

                (8)     the Company shall have delivered to the Trustee an
                        Officers' Certificate and an Opinion of Counsel, each
                        stating that all conditions precedent provided for or
                        relating to the Legal Defeasance or the Covenant
                        Defeasance have been complied with.

        Section 8.05.   Deposited Money and Government Securities to be Held in
Trust; Other Miscellaneous Provisions.

        Subject to Section 8.06 hereof, all money and non-callable Government
Securities (including the proceeds thereof) deposited with the Trustee (or other
qualifying trustee, collectively for purposes of this Section 8.05, the
"Trustee") pursuant to Section 8.04 hereof in respect of the outstanding Notes
shall be held in trust and applied by the Trustee, in accordance with the
provisions of such Notes and this Indenture, to the payment, either directly or
through any Paying Agent (including the Company acting as Paying Agent) as the
Trustee may determine, to the Holders of such Notes of all sums due and to
become due thereon in respect of Accreted Value, Liquidated Damages and premium,
if any, but such money need not be segregated from other funds except to the
extent required by law.

        The Company shall pay and indemnify the Trustee against any tax, fee or
other charge imposed on or assessed against the cash or non-callable Government
Securities deposited pursuant to Section 8.04 hereof or the Accreted Value,
Liquidated Damages and premium, if any, received in respect thereof other than
any such tax, fee or other charge which by law is for the account of the Holders
of the outstanding Notes.

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        Anything in this Article 8 to the contrary notwithstanding, the Trustee
shall deliver or pay to the Company from time to time upon the request of the
Company any money or non-callable Government Securities held by it as provided
in Section 8.04 hereof which, in the opinion of a nationally recognized firm of
independent public accountants expressed in a written certification thereof
delivered to the Trustee (which may be the opinion delivered under clause (1) of
Section 8.04 hereof), are in excess of the amount thereof that would then be
required to be deposited to effect an equivalent Legal Defeasance or Covenant
Defeasance.

        Section 8.06.   Repayment to Company.

        Any money deposited with the Trustee or any Paying Agent, or then held
by the Company, in trust for the payment of the Accreted Value, Liquidated
Interest or premium, if any, on any Note and remaining unclaimed for two years
after such Accreted Value, Liquidated Damages and premium, if any, has become
due and payable shall be paid to the Company on its request or (if then held by
the Company) shall be discharged from such trust; and the Holder of such Note
shall thereafter look only to the Company for payment thereof, and all liability
of the Trustee or such Paying Agent with respect to such trust money, and all
liability of the Company as trustee thereof, shall thereupon cease; provided,
however, that the Trustee or such Paying Agent, before being required to make
any such repayment, may at the expense of the Company cause to be published
once, in The New York Times and The Wall Street Journal (national edition),
notice that such money remains unclaimed and that, after a date specified
therein, which shall not be less than 30 days from the date of such notification
or publication, any unclaimed balance of such money then remaining shall be
repaid to the Company.

        Section 8.07.   Reinstatement.

        If the Trustee or Paying Agent is unable to apply any United States
dollars or non-callable Government Securities in accordance with Section 8.02 or
8.03 hereof, as the case may be, by reason of any order or judgment of any court
or governmental authority enjoining, restraining or otherwise prohibiting such
application, then the Company's and each Guarantor's obligations under this
Indenture and the Notes and the Note Guarantees shall be revived and reinstated
as though no deposit had occurred pursuant to Section 8.02 or 8.03 hereof until
such time as the Trustee or Paying Agent is permitted to apply all such money in
accordance with Section 8.02 or 8.03 hereof, as the case may be; provided,
however, that, if the Company makes any payment of Accreted Value of, Liquidated
Damages or premium, if any, on any Note following the reinstatement of its
obligations, the Company shall be subrogated to the rights of the Holders of
such Notes to receive such payment from the money held by the Trustee or Paying
Agent.

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                                    ARTICLE 9

                        AMENDMENT, SUPPLEMENT AND WAIVER

        Section 9.01.   Without Consent of Holders of Notes.

        Notwithstanding Section 9.02 of this Indenture, the Company, the
Guarantors and the Trustee may amend or supplement this Indenture, the Note
Guarantees or the Notes without the consent of any Holder of Notes:

                (1)     to cure any ambiguity, defect or inconsistency;

                (2)     to provide for uncertificated Notes in addition to or in
                        place of certificated Notes or to alter the provisions
                        of Article 2 hereof (including the related definitions)
                        in a manner that does not materially adversely affect
                        any Holder;

                (3)     to provide for the assumption of the Company's
                        obligations to the Holders of the Notes by a successor
                        to the Company pursuant to Article 5 hereof;

                (4)     to make any change that would provide any additional
                        rights or benefits to the Holders of Notes or that does
                        not adversely affect the legal rights under this
                        Indenture of any such Holder;

                (5)     to comply with requirements of the SEC in order to
                        effect or maintain the qualification of this Indenture
                        under the TIA; or

                (6)     to conform the text of this Indenture, the Note
                        Guarantees or the Notes to any provision of the
                        Description of Notes in the Offering Circular to the
                        extent that such provision in such Description of Notes
                        was intended to be a verbatim recitation of a provision
                        of this Indenture, the Note Guarantees or the Notes.

        Upon the request of the Company accompanied by a resolution of its Board
of Directors authorizing the execution of any such amended or supplemental
indenture, and upon receipt by the Trustee of the documents described in Section
7.02 hereof, the Trustee shall join with the Company in the execution of any
amended or supplemental indenture authorized or permitted by the terms of this
Indenture and to make any further appropriate agreements and stipulations that
may be therein contained, but the Trustee shall not be obligated to enter into
such amended or supplemental indenture that affects its own rights, duties or
immunities under this Indenture or otherwise.

        Section 9.02.   With Consent of Holders of Notes.

        Except as provided below in this Section 9.02, the Company and the
Trustee may amend or supplement this Indenture (including Section 3.09, 4.10 and
4.14 hereof), the Note Guarantees

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and the Notes with the consent of the Holders of at least a majority in
aggregate principal amount at maturity of the Notes then outstanding, voting as
a single class, (including, without limitation, consents obtained in connection
with a tender offer or exchange offer for, or purchase of, the Notes), and,
subject to Sections 6.04 and 6.07 hereof, any existing Default or Event of
Default (other than an uncured Default or Event of Default in the payment of the
Accreted Value of, premium or Liquidated Damages, if any, on the Notes, except a
payment default resulting from an acceleration that has been rescinded) or
compliance with any provision of this Indenture, the Note Guarantees or the
Notes may be waived with the consent of the Holders of a majority in aggregate
principal amount at maturity of the then outstanding Notes, voting as a single
class, (including consents obtained in connection with a tender offer or
exchange offer for, or purchase of, the Notes). Without the consent of at least
66?% in aggregate principal amount at maturity of the Notes then outstanding
(including consents obtained in connection with a tender offer or exchange offer
for, or purchase of, the Notes), no waiver or amendment to this Indenture may
make any change in the provisions of Article 11 hereof that adversely affects
the rights of any Holder of the Notes. Section 2.08 hereof shall determine which
Notes are considered to be "outstanding" for purposes of this Section 9.02.

        Upon the request of the Company accompanied by a resolution of its Board
of Directors authorizing the execution of any such amended or supplemental
Indenture, and upon the filing with the Trustee of evidence satisfactory to the
Trustee of the consent of the Holders of Notes as aforesaid, and upon receipt by
the Trustee of the documents described in Section 7.02 hereof, the Trustee shall
join with the Company in the execution of such amended or supplemental indenture
unless such amended or supplemental indenture directly affects the Trustee's own
rights, duties or immunities under this Indenture or otherwise, in which case
the Trustee may in its discretion, but shall not be obligated to, enter into
such amended or supplemental Indenture.

        It shall not be necessary for the consent of the Holders of Notes under
this Section 9.02 to approve the particular form of any proposed amendment or
waiver, but it shall be sufficient if such consent approves the substance
thereof.

        After an amendment, supplement or waiver under this Section 9.02 becomes
effective, the Company shall mail to the Holders of Notes affected thereby a
notice briefly describing the amendment, supplement or waiver. Any failure of
the Company to mail such notice, or any defect therein, shall not, however, in
any way impair or affect the validity of any such amended or supplemental
Indenture or waiver. Subject to Sections 6.04 and 6.07 hereof, the Holders of a
majority in aggregate principal amount at maturity of the Notes then
outstanding, voting as a single class, may waive compliance in a particular
instance by the Company and the Group Guarantors with any provision of this
Indenture, the Note Guarantees or the Notes. However, without the consent of
each Holder affected, an amendment or waiver under this Section 9.02 may not
(with respect to any Notes held by a non-consenting Holder):

                (1)     reduce the principal amount at maturity of Notes whose
                        Holders must consent to an amendment, supplement or
                        waiver;

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                (2)     reduce the principal amount at maturity of or change the
                        fixed maturity of any Note or alter or waive any of the
                        provisions with respect to the redemption of the Notes,
                        except as provided above with respect to Sections 3.09,
                        4.10 and 4.14 hereof, or amend or modify the calculation
                        of Accreted Value so as to reduce the amount of the
                        Accreted Value of the Notes;

                (3)     waive a Default or Event of Default in the payment of
                        the Accreted Value of, or premium, or Liquidated
                        Damages, if any, on the Notes (except a rescission of
                        acceleration of the Notes by the Holders of at least a
                        majority in aggregate principal amount at maturity of
                        the Notes then outstanding and a waiver of the payment
                        default that resulted from such acceleration);

                (4)     make any Note payable in money other than that stated in
                        the Notes;

                (5)     make any change in the provisions of this Indenture
                        relating to waivers of past Defaults or the rights of
                        Holders of Notes to receive payments of the Accreted
                        Value of, or premium or Liquidated Damages, if any, on
                        the Notes;

                (6)     waive a redemption payment except as provided above with
                        respect to Sections 3.09, 4.10 or 4.14 hereof;

                (7)     release any Guarantor from any of its obligations under
                        its Note Guarantee or this Indenture, except in
                        accordance with the terms of this Indenture; or

                (8)     make any change in Section 6.04 or 6.07 hereof or in the
                        foregoing amendment and waiver provisions.

        Section 9.03.   Compliance with Trust Indenture Act.

        Every amendment or supplement to this Indenture or the Notes shall be
set forth in a amended or supplemental indenture that complies with the TIA as
then in effect.

        Section 9.04.   Revocation and Effect of Consents.

        Until an amendment, supplement or waiver becomes effective, a consent to
it by a Holder of a Note is a continuing consent by the Holder of a Note and
every subsequent Holder of a Note or portion of a Note that evidences the same
debt as the consenting Holder's Note, even if notation of the consent is not
made on any Note. However, any such Holder of a Note or subsequent Holder of a
Note may revoke the consent as to its Note if the Trustee receives written
notice of revocation before the date the waiver, supplement or amendment becomes
effective. An amendment, supplement or waiver becomes effective in accordance
with its terms and thereafter binds every Holder.

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        Section 9.05.   Notation on or Exchange of Notes.

        The Trustee may place an appropriate notation about an amendment,
supplement or waiver on any Note thereafter authenticated. The Company in
exchange for all Notes may issue and the Trustee shall, upon receipt of an
Authentication Order, authenticate new Notes that reflect the amendment,
supplement or waiver.

        Failure to make the appropriate notation or issue a new Note shall not
affect the validity and effect of such amendment, supplement or waiver.

        Section 9.06.   Trustee to Sign Amendments, etc.

        The Trustee shall sign any amended or supplemental Indenture authorized
pursuant to this Article 9 if the amendment or supplement does not adversely
affect the rights, duties, liabilities or immunities of the Trustee. The Company
may not sign an amendment or supplemental indenture until the Board of Directors
approves it. In executing any amended or supplemental indenture, the Trustee
shall be entitled to receive and (subject to Section 7.01 hereof) shall be fully
protected in relying upon, in addition to the documents required by Section
13.04 hereof, an Officer's Certificate and an Opinion of Counsel stating that
the execution of such amended or supplemental indenture is authorized or
permitted by this Indenture.

                                   ARTICLE 10

                                 NOTE GUARANTEES

        Section 10.01.  Guarantee.

        The provisions of this Article 10 shall apply only to (i) the Guarantors
listed on the signature pages hereto upon the consummation of the Escrow Corp.
Merger and (ii) with respect to any future Wholly Owned Domestic Restricted
Subsidiaries of the Company or of any of the Sister Guarantors, if any, upon the
execution of one or more supplemental indentures to this Indenture in the form
of Exhibit C to this Indenture in compliance with the requirements of Section
4.18 of this Indenture.

        Subject to this Article 10, each of the Guarantors hereby, jointly and
severally, unconditionally guarantees to each Holder of a Note authenticated and
delivered by the Trustee and to the Trustee and its successors and assigns,
irrespective of the validity and enforceability of this Indenture, the Notes or
the Obligations of the Company hereunder or thereunder, that: (a) the Accreted
Value of, and Liquidated Damages, if any, on, the Notes shall be promptly paid
in full when due, whether at maturity, by acceleration, redemption or otherwise,
and all other Obligations of the Company to the Holders or the Trustee hereunder
or thereunder shall be promptly paid in full or performed, all in accordance
with the terms hereof and thereof; and (b) in case of any extension of time of
payment or renewal of any Notes or any of such other Obligations, that same
shall be promptly paid in full when due or performed in accordance with the
terms of the extension or renewal, whether at stated maturity, by acceleration
or otherwise. Failing payment when due of any amount so guaranteed or any
performance so guaranteed for

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whatever reason, the Guarantors shall be jointly and severally obligated to pay
the same immediately. Each Guarantor agrees that this is a guarantee of payment
and not a guarantee of collection.

        The Guarantors hereby agree that their obligations hereunder shall be
unconditional, irrespective of the validity, regularity or enforceability of the
Notes or this Indenture, the absence of any action to enforce the same, any
waiver or consent by any Holder of the Notes with respect to any provisions
hereof or thereof, the recovery of any judgment against the Company, any action
to enforce the same or any other circumstance which might otherwise constitute a
legal or equitable discharge or defense of a guarantor. Each Guarantor hereby
waives diligence, presentment, demand of payment, filing of claims with a court
in the event of insolvency or bankruptcy of the Company, any right to require a
proceeding first against the Company, protest, notice and all demands whatsoever
and covenant that this Note Guarantee shall not be discharged except by complete
performance of the obligations contained in the Notes and this Indenture.

        If any Holder or the Trustee is required by any court or otherwise to
return to the Company, the Guarantors or any custodian, trustee, liquidator or
other similar official acting in relation to either the Company or the
Guarantors, any amount paid by either to the Trustee or such Holder, this Note
Guarantee, to the extent theretofore discharged, shall be reinstated in full
force and effect.

        Each Guarantor agrees that it shall not be entitled to any right of
subrogation in relation to the Holders in respect of any obligations guaranteed
hereby until payment in full of all obligations guaranteed hereby. Each
Guarantor further agrees that, as between the Guarantors, on the one hand, and
the Holders and the Trustee, on the other hand, (x) the maturity of the
obligations guaranteed hereby may be accelerated as provided in Article 6 hereof
for the purposes of this Note Guarantee, notwithstanding any stay, injunction or
other prohibition preventing such acceleration in respect of the obligations
guaranteed hereby, and (y) in the event of any declaration of acceleration of
such obligations as provided in Article 6 hereof, such obligations (whether or
not due and payable) shall forthwith become due and payable by the Guarantors
for the purpose of this Note Guarantee. The Guarantors shall have the right to
seek contribution from any non-paying Guarantor so long as the exercise of such
right does not impair the rights of the Holders under the Note Guarantee.

        Section 10.02.  Subordination of Note Guarantee

        The Obligations of each Guarantor under its Note Guarantee pursuant to
this Article 10 shall be subordinated to the Senior Debt of such Guarantor on
the same basis as the Notes are subordinated to Senior Debt of the Company.

        Section 10.03.  Limitation on Guarantor Liability.

        Each Guarantor, and by its acceptance of Notes, each Holder, hereby
confirms that it is the intention of all such parties that the Note Guarantee of
such Guarantor not constitute a fraudulent transfer or conveyance for purposes
of Bankruptcy Law, the Uniform Fraudulent Conveyance Act, the Uniform Fraudulent
Transfer Act or any similar federal or state law to the

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extent applicable to any Note Guarantee. To effectuate the foregoing intention,
the Trustee, the Holders and the Guarantors hereby irrevocably agree that the
obligations of such Guarantor shall not exceed an amount that, after giving
effect to such maximum amount and all other contingent and fixed liabilities of
such Guarantor that are relevant under such laws, and after giving effect to any
collections from, rights to receive contribution from or payments made by or on
behalf of any other Guarantor in respect of the obligations of such other
Guarantor under this Article 10, would result in the obligations of such
Guarantor under its Note Guarantee constituting a fraudulent transfer or
conveyance.

        Section 10.04.  Evidence of Note Guarantee.

        To evidence its Note Guarantee set forth in Section 10.01, each
Guarantor hereby agrees to execute this Indenture with effect as of the
consummation of the Escrow Corp. Merger or, in the case of a Person becoming a
Guarantor pursuant to Section 4.18 hereof, to execute a supplemental indenture
in the form attached as Exhibit B.

        Section 10.05.  Guarantors May Consolidate, etc., on Certain Terms.

        Except as otherwise provided in Section 10.06, no Group Guarantor may
sell or otherwise dispose of all or substantially all of its assets to, or
consolidate with or merge with or into (whether or not such Guarantor is the
surviving Person) another Person other than the Company or another Group
Guarantor, unless:

                (1)     subject to Section 10.06 hereof, either (i) the Person
                        acquiring the property in any such sale or disposition
                        or the Person formed by or surviving any such
                        consolidation or merger unconditionally assumes all the
                        Obligations of that Group Guarantor, pursuant to a
                        supplemental indenture in the form attached as Exhibit
                        B, under the Notes, the Indenture, the Note Guarantee
                        and the Registration Rights Agreement on the terms set
                        forth herein or therein or (ii) the Net Proceeds of such
                        sale or other disposition are applied in accordance with
                        the applicable provisions of this Indenture; and

                (2)     immediately after giving effect to such transaction, no
                        Default or Event of Default exists.

        In case of any such consolidation or merger and upon the assumption by
the successor Person, by supplemental indenture, executed and delivered to the
Trustee in the form attached as Exhibit B and the due and punctual performance
of all of the covenants and conditions of this Indenture to be performed by the
Guarantor, such successor Person shall succeed to and be substituted for the
Guarantor with the same effect as if it had been named herein as a Guarantor.
All the Note Guarantees so issued shall in all respects have the same legal rank
and benefit under this Indenture as the Note Guarantees theretofore and
thereafter issued in accordance with the terms of this Indenture as though all
of such Note Guarantees had been issued at the date of the execution hereof.

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        Except as set forth in Articles 4 and 5 hereof, and notwithstanding
clauses (1) and (2) above, nothing contained in this Indenture or in any of the
Notes shall prevent any consolidation or merger of a Guarantor with or into the
Company or another Guarantor, or shall prevent any sale or conveyance of the
property of a Guarantor as an entirety or substantially as an entirety to the
Company or another Guarantor.

        Section 10.06.  Releases.

        The Note Guarantee of a Group Guarantor shall be released:

                (1)     in connection with any sale or other disposition of all
                        or substantially all of the assets of that Group
                        Guarantor (including by way of merger or consolidation)
                        to a Person that is not (either before or after giving
                        effect to such transaction) the Company, a Sister
                        Guarantor or a Restricted Subsidiary, if the sale or
                        other disposition complies with Section 4.10 hereof;

                (2)     in connection with any sale of Capital Stock of a Group
                        Guarantor (as a result of which such Guarantor is no
                        longer a Subsidiary of the Company or a Subsidiary of a
                        Sister Guarantor or, in the case of the Sister
                        Guarantors, a Subsidiary of the Parent) to a Person that
                        is not (either before or after giving effect to such
                        transaction) a Subsidiary of the Company or a Subsidiary
                        of a Sister Guarantor or, in the case of the Sister
                        Guarantors, a Subsidiary of the Parent, if the sale
                        complies with Section 4.10 hereof and, if not a sale of
                        all such Capital Stock, the remaining Investment of the
                        Company, the Sister Guarantors and the Restricted
                        Subsidiaries in such Group Guarantor complies with
                        Section 4.07 hereof;

                (3)     if the Company or a Sister Guarantor designates such
                        Group Guarantor as an Unrestricted Subsidiary in
                        accordance with the applicable provisions of this
                        Indenture; or

                (4)     if such Group Guarantor is released from its Guarantee
                        under the Credit Agreement or is released from its
                        obligations as a co-borrower under the Credit Agreement.

        Any Guarantor not released from its obligations under its Note Guarantee
shall remain liable for the Accreted Value of the Notes and for the other
obligations of any Guarantor under this Indenture as provided in this Article
10. The Note Guarantee of the Parent shall be released if the Parent is released
from its Guarantee under the Credit Agreement. If a Sister Guarantor is released
from its Note Guarantee, it shall also be released from all of its Obligations
under this Indenture. If any Group Guarantor is released from its Note
Guarantee, its Restricted Subsidiaries shall also be released from their Note
Guarantees.

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                                   ARTICLE 11

                                  SUBORDINATION

        Section 11.01.  Agreement to Subordinate.

        The Company agrees, and each Holder by accepting a Note agrees, that the
Indebtedness evidenced by the Notes is subordinated in right of payment, to the
extent and in the manner provided in this Article 11, to the prior payment in
full of all Senior Debt (whether outstanding on the date hereof or hereafter
created, incurred, assumed or guaranteed), and that the subordination is for the
benefit of the holders of Senior Debt.

        Section 11.02.  Liquidation; Dissolution; Bankruptcy.

        Upon any distribution to creditors of the Company in a liquidation or
dissolution of the Company or in a bankruptcy, reorganization, insolvency,
receivership or similar proceeding relating to the Company or its property, in
an assignment for the benefit of the Company's creditors or any marshaling of
the Company's assets and liabilities:

                (1)     holders of Senior Debt shall be entitled to receive
                        payment in full of all Obligations due in respect of
                        such Senior Debt (including interest after the
                        commencement of any bankruptcy proceeding at the rate
                        specified in the applicable Senior Debt) before the
                        Holders of Notes shall be entitled to receive any
                        payment with respect to the Notes (except that Holders
                        of Notes may receive and retain Permitted Junior
                        Securities and payments made from any defeasance trust
                        created pursuant to Section 8.01 hereof); and

                (2)     until all Obligations with respect to Senior Debt (as
                        provided in clause (1) above) are paid in full, any
                        distribution to which Holders would be entitled but for
                        this Article 11 shall be made to holders of Senior Debt
                        (except that Holders of Notes may receive and retain
                        Permitted Junior Securities and payments made from any
                        defeasance trust created pursuant to Section 8.01
                        hereof), as their interests may appear.

        Section 11.03.  Default on Designated Senior Debt.

        (a)     The Company may not make any payment or distribution to the
Trustee or any Holder in respect of Obligations with respect to the Notes and
may not acquire from the Trustee or any Holder any Notes for cash or property
(other than Permitted Junior Securities and payments made from any defeasance
trust created pursuant to Section 8.01 hereof) until all principal and other
Obligations with respect to the Senior Debt have been paid in full if:

                (1)     a payment default on Designated Senior Debt occurs and
                        is continuing beyond any applicable grace period in the
                        agreement,

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                        indenture or other document governing such Designated
                        Senior Debt; or

                (2)     any other default occurs and is continuing on any series
                        of Designated Senior Debt that permits holders of that
                        series of Designated Senior Debt to accelerate its
                        maturity and the Trustee receives a notice of such
                        default (a "Payment Blockage Notice") from the Company
                        or the holders of any Designated Senior Debt or their
                        Representative. If the Trustee receives any such Payment
                        Blockage Notice, no subsequent Payment Blockage Notice
                        shall be effective for purposes of this Section unless
                        and until (A) at least 360 days have elapsed since the
                        effectiveness of the immediately prior Payment Blockage
                        Notice and (B) all scheduled payments of Accreted Value,
                        Liquidated Damages and premium, if any, on the Notes
                        that have come due have been paid in full in cash.

        No nonpayment default that existed or was continuing on the date of
delivery of any Payment Blockage Notice to the Trustee may be, or may be made,
the basis for a subsequent Payment Blockage Notice unless such default has been
cured or waived for a period of not less than 180 days.

        (b)     The Company may and shall resume payments on and distributions
in respect of the Notes and may acquire them upon the earlier of:

                (1)     in the case of a payment default, upon the date upon
                        which such default is cured or waived, or

                (2)     in the case of a nonpayment default, upon the earlier of
                        the date on which such nonpayment default is cured or
                        waived or 179 days after the date on which the
                        applicable Payment Blockage Notice is received, unless
                        the maturity of any Designated Senior Debt has been
                        accelerated,

if this Article 11 otherwise permits the payment, distribution or acquisition at
the time of such payment or acquisition.

        Section 11.04.  Acceleration of Notes.

        If payment of the Notes is accelerated because of an Event of Default,
the Company shall promptly notify holders of Senior Debt of the acceleration.

        Section 11.05.  When Distribution Must Be Paid Over.

        In the event that the Trustee or any Holder receives any payment of any
Obligations with respect to the Notes (other than Permitted Junior Securities
and payments made from any defeasance trust created pursuant to Section 8.01
hereof) at a time when the Trustee or such

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Holder, as applicable, has actual knowledge that such payment is prohibited by
Section 11.03 hereof, such payment shall be held by the Trustee or such Holder,
in trust for the benefit of, and shall be paid forthwith over and delivered,
upon written request, to, the holders of Senior Debt as their interests may
appear or their Representative under the agreement, indenture or other document
(if any) pursuant to which Senior Debt may have been issued, as their respective
interests may appear, for application to the payment of all Obligations with
respect to Senior Debt remaining unpaid to the extent necessary to pay such
Obligations in full in accordance with their terms, after giving effect to any
concurrent payment or distribution to or for the holders of Senior Debt.

        With respect to the holders of Senior Debt, the Trustee undertakes to
perform only those obligations on the part of the Trustee as are specifically
set forth in this Article 11, and no implied covenants or obligations with
respect to the holders of Senior Debt shall be read into this Indenture against
the Trustee. The Trustee shall not be deemed to owe any fiduciary duty to the
holders of Senior Debt, and shall not be liable to any such holders if the
Trustee pays over or distributes to or on behalf of Holders or the Company or
any other Person money or assets to which any holders of Senior Debt are then
entitled by virtue of this Article 11, except if such payment is made as a
result of the willful misconduct or gross negligence of the Trustee.

        Section 11.06.  Notice by Company

        The Company shall promptly notify the Trustee and the Paying Agent of
any facts known to the Company that would cause a payment of any Obligations
with respect to the Notes to violate this Article 11, but failure to give such
notice shall not affect the subordination of the Notes to the Senior Debt as
provided in this Article 11.

        Section 11.07.  Subrogation.

        After all Senior Debt is paid in full and until the Notes are paid in
full, Holders of Notes shall be subrogated (equally and ratably with all other
Indebtedness pari passu with the Notes) to the rights of holders of Senior Debt
to receive distributions applicable to Senior Debt to the extent that
distributions otherwise payable to the Holders of Notes have been applied to the
payment of Senior Debt. A distribution made under this Article 11 to holders of
Senior Debt that otherwise would have been made to Holders of Notes is not, as
between the Company and Holders, a payment by the Company on the Notes.

        Section 11.08.  Relative Rights.

        This Article 11 defines the relative rights of Holders of Notes and
holders of Senior Debt. Nothing in this Indenture shall:

                (1)     impair, as between the Company and Holders of Notes, the
                        obligation of the Company, which is absolute and
                        unconditional, to pay Accreted Value of, Liquidated
                        Damages and premium, if any, on the Notes in accordance
                        with their terms;

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                (2)     affect the relative rights of Holders of Notes and
                        creditors of the Company other than their rights in
                        relation to holders of Senior Debt; or

                (3)     prevent the Trustee or any Holder of Notes from
                        exercising its available remedies upon a Default or
                        Event of Default, subject to the rights of holders and
                        owners of Senior Debt to receive distributions and
                        payments otherwise payable to Holders of Notes.

        If the Company fails because of this Article 11 to pay Accreted Value
of, Liquidated Damages or premium, if any, on a Note on the due date, the
failure is still a Default or Event of Default.

        Section 11.09.  Subordination May Not Be Impaired by Company

        No right of any holder of Senior Debt to enforce the subordination of
the Indebtedness evidenced by the Notes may be impaired by any act or failure to
act by the Company or any Holder or by the failure of the Company or any Holder
to comply with this Indenture.

        Section 11.10.  Distribution or Notice to Representative

        Whenever a distribution is to be made or a notice given to holders of
Senior Debt, the distribution may be made and the notice given to their
Representative.

        Upon any payment or distribution of assets of the Company referred to in
this Article 11, the Trustee and the Holders of Notes shall be entitled to rely
upon any order or decree made by any court of competent jurisdiction or upon any
certificate of such Representative or of the liquidating trustee or agent or
other Person making any distribution to the Trustee or to the Holders of Notes
for the purpose of ascertaining the Persons entitled to participate in such
distribution, the holders of the Senior Debt and other Indebtedness of the
Company, the amount thereof or payable thereon, the amount or amounts paid or
distributed thereon and all other facts pertinent thereto or to this Article 11.

        Section 11.11.  Rights of Trustee and Paying Agent

        Notwithstanding the provisions of this Article 11 or any other provision
of this Indenture, the Trustee shall not be charged with knowledge of the
existence of any facts that would prohibit the making of any payment or
distribution by the Trustee, and the Trustee and the Paying Agent may continue
to make payments on the Notes, unless the Trustee has received at its Corporate
Trust Office at least five Business Days prior to the date of such payment
written notice of facts that would cause the payment of any Obligations with
respect to the Notes to violate this Article 11. Only the Company or a
Representative may give the notice. Nothing in this Article 11 shall impair the
claims of, or payments to, the Trustee under or pursuant to Section 7.07 hereof.

        The Trustee in its individual or any other capacity may hold Senior Debt
with the same rights it would have if it were not Trustee. Any Agent may do the
same with like rights.

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        Section 11.12.  Authorization to Effect Subordination.

        Each Holder of Notes, by the Holder's acceptance thereof, authorizes and
directs the Trustee on such Holder's behalf to take such action as may be
necessary or appropriate to effectuate the subordination as provided in this
Article 11, and appoints the Trustee to act as such Holder's attorney-in-fact
for any and all such purposes. If the Trustee does not file a proper proof of
claim or proof of debt in the form required in any proceeding referred to in
Section 6.09 hereof at least 30 days before the expiration of the time to file
such claim, the Representatives are hereby authorized to file an appropriate
claim for and on behalf of the Holders of the Notes.

        Section 11.13.  Amendments.

        The provisions of this Article 11 may not be amended or modified without
the written consent of the holders of all Senior Debt. In addition, any
amendment to, or waiver of, the provisions of this Article 11 that adversely
affects the rights of the Holders of the Notes shall require the consent of the
Holders of at least 66?% in aggregate principal amount at maturity of Notes then
outstanding.

                                   ARTICLE 12

                           SATISFACTION AND DISCHARGE

        Section 12.01.  Satisfaction and Discharge

        This Indenture shall be discharged and shall cease to be of further
effect as to all Notes issued hereunder, when:

                (1)     either

                        (a)     all Notes that have been authenticated, except
                                lost, stolen or destroyed Notes that have been
                                replaced or paid and Notes for whose payment
                                money has been deposited in trust and thereafter
                                repaid to the Company, have been delivered to
                                the Trustee for cancellation; or

                        (b)     all Notes that have not been delivered to the
                                Trustee for cancellation have become due and
                                payable by reason of the mailing of a notice of
                                redemption or otherwise or shall become due and
                                payable within one year and the Company or any
                                Guarantor has irrevocably deposited or caused to
                                be deposited with the Trustee as trust funds in
                                trust solely for the benefit of the Holders,
                                cash in U.S. dollars, non-callable Government
                                Securities, or a combination of cash in U.S.
                                dollars and non-callable Government Securities,
                                in amounts as shall be sufficient without
                                consideration of any reinvestment of interest,
                                to pay and discharge the entire

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                                indebtedness on the Notes not delivered to the
                                Trustee for cancellation for Accreted Value,
                                premium and Liquidated Damages, if any;

                (2)     no Default or Event of Default has occurred and is
                        continuing on the date of the deposit or shall occur as
                        a result of the deposit and the deposit shall not result
                        in a breach or violation of, or constitute a default
                        under, any other instrument to which the Company or any
                        Guarantor is a party or by which the Company or any
                        Guarantor is bound;

                (3)     the Company or any Guarantor has paid or caused to be
                        paid all sums payable by it under this Indenture; and

                (4)     the Company has delivered irrevocable instructions to
                        the Trustee under this Indenture to apply the deposited
                        money toward the payment of the Notes at maturity or the
                        redemption date, as the case may be.

        In addition, the Company must deliver an Officers' Certificate to the
Trustee stating that all conditions precedent to satisfaction and discharge have
been satisfied.

        Notwithstanding the satisfaction and discharge of this Indenture, if
money has been deposited with the Trustee pursuant to subclause (b) of clause
(1) of this Section, the provisions of Section 12.02 and Section 8.06 shall
survive. In addition, nothing in this Section 12.01 shall be deemed to discharge
those provisions of Section 7.07 hereof, that, by their terms, survive the
satisfaction and discharge of this Indenture.

        Section 12.02.  Notices

        Subject to the provisions of Section 8.06, all money deposited with the
Trustee pursuant to Section 12.01 shall be held in trust and applied by it, in
accordance with the provisions of the Notes and this Indenture, to the payment,
either directly or through any Paying Agent (including the Company acting as its
own Paying Agent) as the Trustee may determine, to the Persons entitled thereto,
of the Accreted Value, Liquidated Damages and premium, if any, for whose payment
such money has been deposited with the Trustee; but such money need not be
segregated from other funds except to the extent required by law.

        If the Trustee or Paying Agent is unable to apply any money or
Government Securities in accordance with Section 12.01 by reason of any legal
proceeding or by reason of any order or judgment of any court or governmental
authority enjoining, restraining or otherwise prohibiting such application, the
Company's and any Guarantor's obligations under this Indenture and the Notes
shall be revived and reinstated as though no deposit had occurred pursuant to
Section 12.01; provided that if the Company has made any payment of Accreted
Value, Liquidated Damages or premium, if any, on any Notes because of the
reinstatement of its obligations, the

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Company shall be subrogated to the rights of the Holders of such Notes to
receive such payment from the money or Government Securities held by the Trustee
or Paying Agent.

                                   ARTICLE 13

                                  MISCELLANEOUS

        Section 13.01.  Trust Indenture Act Controls.

        If any provision of this Indenture limits, qualifies or conflicts with
the duties imposed by TIA Section 318(c), the imposed duties shall control.

        Section 13.02.  Notices.

        Any notice or communication by the Company, any Guarantor, or the
Trustee to the others is duly given if in writing and delivered in Person or
mailed by first class mail (registered or certified, return receipt requested),
telex, telecopier or overnight air courier guaranteeing next day delivery, to
the others' address:

        If to the Company and/or any Guarantor:

        c/o American Tower Corporation
        116 Huntington Avenue
        Boston, MA 02116
        Telecopier No.:  (617) 375-7575
        Attention:  Chief Financial Officer and
                    Treasurer and Executive
                    Vice President and General Counsel

        If to the Trustee:

        The Bank of New York
        101 Barclay Street, 21W
        New York, New York  10286
        Telecopier No.:  (212) 815-5915
        Attention:  Corporate Trustee Administration Department

        The Company, any Guarantor or the Trustee, by notice to the others, may
designate additional or different addresses for subsequent notices or
communications.

        All notices and communications (other than those sent to Holders) shall
be deemed to have been duly given: at the time delivered by hand, if personally
delivered; five Business Days after being deposited in the mail, postage
prepaid, if mailed; when receipt acknowledged, if telecopied; and the next
Business Day after timely delivery to the courier, if sent by overnight air
courier guaranteeing next day delivery.

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        Any notice or communication to a Holder shall be mailed by first class
mail, certified or registered, return receipt requested, or by overnight air
courier guaranteeing next day delivery to its address shown on the register kept
by the Registrar. Any notice or communication shall also be so mailed to any
Person described in TIA Section 313(c), to the extent required by the TIA.
Failure to mail a notice or communication to a Holder or any defect in it shall
not affect its sufficiency with respect to other Holders.

        If a notice or communication is mailed in the manner provided above
within the time prescribed, it is duly given, whether or not the addressee
receives it.

        If the Company mails a notice or communication to Holders, it shall mail
a copy to the Trustee and each Agent at the same time.

        Section 13.03.  Communication by Holders of Notes with Other Holders of
Notes.

        Holders may communicate pursuant to TIA Section 312(b) with other
Holders with respect to their rights under this Indenture or the Notes. The
Company, the Trustee, the Registrar and anyone else shall have the protection of
TIA Section 312(c).

        Section 13.04.  Certificate and Opinion as to Conditions Precedent.

        Upon any request or application by the Company to the Trustee to take
any action under this Indenture, the Company shall furnish to the Trustee:

        (a)     an Officers' Certificate in form and substance reasonably
satisfactory to the Trustee (which shall include the statements set forth in
Section 13.05 hereof) stating that, in the opinion of the signers, all
conditions precedent and covenants, if any, provided for in this Indenture
relating to the proposed action have been satisfied; and

        (b)     an Opinion of Counsel in form and substance reasonably
satisfactory to the Trustee (which shall include the statements set forth in
Section 13.05 hereof) stating that, in the opinion of such counsel, all such
conditions precedent and covenants have been satisfied.

        Section 13.05.  Statements Required in Certificate or Opinion.

        Each certificate or opinion with respect to compliance with a condition
or covenant provided for in this Indenture (other than a certificate provided
pursuant to TIA Section 314(a)(4)) shall comply with the provisions of TIA
Section 314(e) and shall include:

        (a)     a statement that the Person making such certificate or opinion
has read such covenant or condition;

        (b)     a brief statement as to the nature and scope of the examination
or investigation upon which the statements or opinions contained in such
certificate or opinion are based;

                                       100

<PAGE>

        (c)     a statement that, in the opinion of such Person, he, she or it
has made such examination or investigation as is necessary to enable such Person
to express an informed opinion as to whether or not such covenant or condition
has been satisfied; and

        (d)     a statement as to whether or not, in the opinion of such Person,
such condition or covenant has been satisfied.

        Section 13.06.  Rules by Trustee and Agents.

        The Trustee may make reasonable rules for action by or at a meeting of
Holders. The Registrar or Paying Agent may make reasonable rules and set
reasonable requirements for its functions; provided that no such rule shall
conflict with the terms of this Indenture or the TIA.

        Section 13.07.  No Personal Liability of Directors, Officers, Employees
and Stockholders.

        No past, present or future director, officer, employee, incorporator,
stockholder or agent of the Company, as such, shall have any liability for any
obligations of the Company or the Guarantors under the Notes, this Indenture or
the Note Guarantees or for any claim based on, in respect of, or by reason of,
such obligations or their creation. Each Holder by accepting a Note waives and
releases all such liability. The waiver and release are part of the
consideration for issuance of the Notes.

        Section 13.08.  Governing Law.

        THE INTERNAL LAW OF THE STATE OF NEW YORK SHALL GOVERN AND BE USED TO
CONSTRUE THIS INDENTURE AND THE NOTES WITHOUT GIVING EFFECT TO APPLICABLE
PRINCIPLES OF CONFLICTS OF LAW TO THE EXTENT THAT THE APPLICATION OF THE LAWS OF
ANOTHER JURISDICTION WOULD BE REQUIRED THEREBY.

        Section 13.09.  No Adverse Interpretation of Other Agreements.

        This Indenture may not be used to interpret any other indenture, loan or
debt agreement of the Company or its Subsidiaries or of any other Person. Any
such indenture, loan or debt agreement may not be used to interpret this
Indenture.

        Section 13.10.  Successors.

        All agreements of the Company in this Indenture and the Notes shall bind
its successors. All agreements of the Trustee in this Indenture shall bind its
successors. All agreements of each Guarantor in this Indenture shall bind its
successors, except as otherwise provided in Section 10.06 hereof.

                                       101

<PAGE>

        Section 13.11.  Severability.

        In case any provision in this Indenture or in the Notes shall be
invalid, illegal or unenforceable, the validity, legality and enforceability of
the remaining provisions shall not in any way be affected or impaired thereby.

        Section 13.12.  Counterpart Originals.

        The parties may sign any number of copies of this Indenture. Each signed
copy shall be an original, but all of them together represent the same
agreement.

        Section 13.13.  Table of Contents, Headings, etc.

        The Table of Contents, Cross-Reference Table and Headings of the
Articles and Sections of this Indenture have been inserted for convenience of
reference only, are not to be considered a part of this Indenture and shall in
no way modify or restrict any of the terms or provisions hereof.

                         [Signatures on following page]

                                       102

<PAGE>

                                   SIGNATURES

Dated as of January 29, 2003

                                            AMERICAN TOWER ESCROW CORPORATION

                                            By:  /s/ Bradley E. Singer
                                                 -------------------------------
                                                 Name:  Bradley E. Singer
                                                 Title: President

Attest:

  /s/ Justin D. Benincasa
--------------------------------------
Name:   Justin D. Benincasa
Title:  Vice President

                                            THE BANK OF NEW YORK

                                            By:  /s/ Kisha A. Holder
                                                 -------------------------------
                                                 Name:  Kisha A. Holder
                                                 Title: Assistant Treasurer

                                       103

<PAGE>

        Each of the Guarantors agrees to be bound by the terms and conditions of
this Indenture, as of the date of the consummation of the Escrow Corp. Merger.
Prior to such date, the Guarantors shall not be deemed to be a party to this
Indenture and shall not be bound by the terms and conditions thereof.

                                            American Tower Corporation
                                            ATC GP, Inc.
                                            American Tower Delaware Corporation
                                            American Tower Management, Inc.
                                            ATC LP Inc.
                                            ATC International Holding Corp.
                                            New Loma Communications, Inc.
                                            Towersites Monitoring, Inc.
                                            Kline Iron & Steel Co., Inc.
                                            Carolina Towers, Inc.
                                            ATC Tower Services, Inc.
                                            UniSite, Inc.
                                            ATC South America Holding Corp.
                                            American Tower International, Inc.

                                            By:  /s/ Justin D. Benincasa
                                                 -------------------------------
                                                 Name:  Justin D. Benincasa
                                                 Title: Sr. Vice President

Attest:

  /s/ Bradley E. Singer
--------------------------------------
Name:   Bradley E. Singer
Title:  Chief Financial Officer and
        Treasurer of American Tower
        Corporation

                                       104

<PAGE>

                                            American Tower LLC

                                            By:  American Tower Corporation,
                                                 its sole member and manager

                                            By:  /s/ Justin D. Benincasa
                                                 -------------------------------
                                                 Name:  Justin D. Benincasa
                                                 Title: Sr. Vice President

Attest:

  /s/ Bradley E. Singer
------------------------------------
Name:   Bradley E. Singer
Title:  Chief Financial Officer and
        Treasurer of American Tower
        Corporation

                                            Towers Of America, L.L.L.P.
                                            ATS/PCS, LLC

                                            By:  American Tower, L.P.,
                                                 its general partner and its
                                                 sole member and manager
                                                 (as applicable)
                                            By:  ATC GP, Inc.,
                                                 its general partner

                                            By:  /s/ Justin D. Benincasa
                                                 -------------------------------
                                                 Name:  Justin D. Benincasa
                                                 Title: Sr. Vice President

Attest:

  /s/ Bradley E. Singer
------------------------------------
Name:   Bradley E. Singer
Title:  Chief Financial Officer and
        Treasurer of American Tower
        Corporation

                                       105

<PAGE>

                                            American Tower PA LLC
                                            Telecom Towers, L.L.C.
                                            ATC South LLC

                                            By:  American Towers, Inc.,
                                                 their sole member and manager

                                            By:  /s/ Justin D. Benincasa
                                                 -------------------------------
                                                 Name:  Justin D. Benincasa
                                                 Title: Sr. Vice President

Attest:

  /s/ Bradley E. Singer
------------------------------------
Name:   Bradley E. Singer
Title:  Chief Financial Officer and
        Treasurer of American Tower
        Corporation

                                            ATC Midwest, LLC

                                            By:  American Tower Management,Inc.,
                                                 its sole member and manager

                                            By:  /s/ Justin D. Benincasa
                                                 -------------------------------
                                                 Name:  Justin D. Benincasa
                                                 Title: Sr. Vice President

Attest:

  /s/ Bradley E. Singer
--------------------------------------
Name:   Bradley E. Singer
Title:  Chief Financial Officer and
        Treasurer of American Tower
        Corporation

                                       106

<PAGE>

                                            MHB Tower Rentals of America, LLC

                                            By:  ATC South LLC, its sole member
                                            By:  American Towers, Inc.,
                                                 its sole member and manager

                                            By:  /s/ Justin D. Benincasa
                                                 -------------------------------
                                                 Name:  Justin D. Benincasa
                                                 Title: Sr. Vice President

Attest:

  /s/ Bradley E. Singer
------------------------------------
Name:   Bradley E. Singer
Title:  Chief Financial Officer and
        Treasurer of American Tower
        Corporation

                                            American Tower, L.P.

                                            By:  ATC GP, Inc.,
                                                 its general partner

                                            By:  /s/ Justin D. Benincasa
                                                 -------------------------------
                                                 Name:  Justin D. Benincasa
                                                 Title: Sr. Vice President

Attest:

  /s/ Bradley E. Singer
------------------------------------
Name:   Bradley E. Singer
Title:  Chief Financial Officer and
        Treasurer of American Tower
        Corporation

                                       107

<PAGE>

                                            Shreveport Tower Company

                                            By:  Telecom Towers, LLC, and
                                                 ATC South, LLC,
                                                 its general partners
                                            By:  American Towers, Inc.,
                                                 their sole member and manager

                                            By:  /s/ Justin D. Benincasa
                                                 -------------------------------
                                                 Name:  Justin D. Benincasa
                                                 Title: Sr. Vice President

Attest:

  /s/ Bradley E. Singer
------------------------------------
Name:   Bradley E. Singer
Title:  Chief Financial Officer and
        Treasurer of American Tower
        Corporation

                                            American Tower Trust #1
                                            American Tower Trust #2

                                            By:  /s/ Justin D. Benincasa
                                                 -------------------------------
                                                 Name:  Justin D. Benincasa
                                                 Title: Trustee

Attest:

  /s/ Bradley E. Singer
------------------------------------
Name:   Bradley E. Singer
Title:  Chief Financial Officer and
        Treasurer of American Tower
        Corporation

                                       108

<PAGE>

                                                                       EXHIBIT A

                                  FORM OF NOTE

                                 [FACE OF NOTE]

[Insert the Global Note Legend, if applicable, pursuant to Section 2.06(f)(i) of
the Indenture]

[Insert the Investment Company Act Legend, if applicable, pursuant to Section
2.06(f)(iii) of the Indenture]

[Insert the OID Legend, if applicable, pursuant to Section 2.06(f)(iv) of the
Indenture]

[Insert the Unit Legend, if applicable, pursuant to Section 2.06(f)(v) of the
Indenture]

[If Restricted Notes, then insert the following legend (the "Private Placement
Legend") - THIS NOTE (OR ITS PREDECESSOR) AND ANY RELATED NOTE GUARANTEE WAS
ORIGINALLY ISSUED IN A TRANSACTION EXEMPT FROM REGISTRATION UNDER THE UNITED
STATES SECURITIES ACT OF 1933 (THE "SECURITIES ACT"), [AND THE COMPANY HAS NOT
BEEN REGISTERED UNDER THE UNITED STATES INVESTMENT COMPANY ACT OF 1940, AS
AMENDED (THE "INVESTMENT COMPANY ACT")] [to be included only in the Notes for so
long as American Tower Escrow Corporation is the obligor]. ACCORDINGLY, THIS
NOTE AND ANY RELATED NOTE GUARANTEE HAS NOT BEEN REGISTERED UNDER THE SECURITIES
ACT AND MAY NOT BE OFFERED, SOLD OR OTHERWISE TRANSFERRED IN THE ABSENCE OF SUCH
REGISTRATION OR AN APPLICABLE EXEMPTION THEREFROM. EACH PURCHASER OF THIS NOTE
IS HEREBY NOTIFIED THAT THE SELLER OF THIS NOTE MAY BE RELYING ON THE EXEMPTION
FROM THE PROVISIONS OF SECTION 5 OF THE SECURITIES ACT PROVIDED BY RULE 144A
THEREUNDER.

THE HOLDER OF THIS NOTE AGREES FOR THE BENEFIT OF THE COMPANY THAT (A) THIS NOTE
MAY BE OFFERED, RESOLD, PLEDGED OR OTHERWISE TRANSFERRED, ONLY (I) IN THE UNITED
STATES TO A PERSON WHOM THE SELLER REASONABLY BELIEVES IS A QUALIFIED
INSTITUTIONAL BUYER (AS DEFINED IN RULE 144A UNDER THE SECURITIES ACT) IN A
TRANSACTION MEETING THE REQUIREMENTS OF RULE 144A, (II) OUTSIDE THE UNITED
STATES IN AN OFFSHORE TRANSACTION IN ACCORDANCE WITH RULE 904 UNDER THE
SECURITIES ACT, (III) PURSUANT TO AN EXEMPTION FROM REGISTRATION UNDER THE
SECURITIES ACT PROVIDED BY RULE 144 THEREUNDER (IF AVAILABLE) OR (IV) PURSUANT
TO AN EFFECTIVE REGISTRATION STATEMENT UNDER THE SECURITIES ACT, IN EACH OF
CASES (I) THROUGH (IV) IN ACCORDANCE WITH ANY APPLICABLE SECURITIES LAWS OF ANY
STATE OF THE UNITED STATES, AND (B) THE HOLDER SHALL, AND EACH SUBSEQUENT HOLDER
IS REQUIRED TO, NOTIFY

<PAGE>

ANY PURCHASER OF THIS NOTE FROM IT OF THE RESALE RESTRICTIONS REFERRED TO IN (A)
ABOVE.

ESCROW CORP., AMERICAN TOWERS, INC., THE TRANSFER AGENT OR THE INDENTURE
TRUSTEE, AS APPLICABLE, SHALL REFUSE TO REGISTER ANY TRANSFER OF THE SECURITIES
IN VIOLATION OF THE FOREGOING.

[If a Regulation S Note, then insert -- THIS NOTE AND ANY RELATED NOTE GUARANTEE
HAS NOT BEEN REGISTERED UNDER THE U.S. SECURITIES ACT OF 1933 (THE "SECURITIES
ACT") AND MAY NOT BE OFFERED, SOLD OR DELIVERED IN THE UNITED STATES OR TO, OR
FOR THE ACCOUNT OR BENEFIT OF, ANY U.S. PERSON, UNLESS THIS NOTE IS REGISTERED
UNDER THE SECURITIES ACT OR AN EXEMPTION FROM THE REGISTRATION REQUIREMENTS
THEREOF IS AVAILABLE.]

                                       A-2

<PAGE>

                              CUSIP/CINS___________

               12.25% Senior Subordinated Discount Notes Due 2008

No. ___                                                               $_________

                        AMERICAN TOWER ESCROW CORPORATION

promises to pay to CEDE & CO. or registered assigns, the principal sum of
__________________________________ DOLLARS on August 1, 2008.

Dated: ____________________

                                    AMERICAN TOWER ESCROW CORPORATION

                                    By:
                                       ----------------------------
                                       Name:
                                       Title:

                                    By:
                                       ----------------------------
                                       Name:
                                       Title:

This is one of the Notes referred to
in the within-mentioned Indenture:

THE BANK OF NEW YORK,
as Trustee

By:
   ----------------------------
   Authorized Signatory

                                       A-3

<PAGE>

                                 [BACK OF NOTE]

               12.25% Senior Subordinated Discount Notes Due 2008

        Capitalized terms used herein shall have the meanings assigned to them
in the Indenture referred to below unless otherwise indicated.

        1.      Interest. American Tower Escrow Corporation (together with its
successors, the "Company"), shall pay no interest on the principal amount of
this Note. The Accreted Value of this Note will increase between the Issue Date
and maturity at a rate of 12.25% per annum calculated on a semi-annual bond
equivalent basis using a 360-day year comprised of twelve 30-day months, such
that the Accreted Value at maturity of this Note will equal the full principal
amount at maturity of this Note. [If Original Notes then insert: If (i) on or
prior to the 90th day following the Issue Date (or such longer period as
required by applicable law), neither a registration statement (the "Exchange
Registration Statement") under the Securities Act, registering a note
substantially identical to this Note (except that such Note will not contain
terms with respect to the Additional Interest payments described below or
transfer restrictions) pursuant to an exchange offer (the "Exchange Offer") nor
a registration statement registering this Note for resale (a "Shelf Registration
Statement") has been filed with the Securities and Exchange Commission, (ii) on
or prior to the 180th day following the Issue Date, neither the Exchange
Registration Statement nor the Shelf Registration Statement has become or been
declared effective, (iii) on or prior to 30 business days following the
Effectiveness Target Date, the Exchange Offer has not been consummated, or (iv)
either the Exchange Registration Statement or, if applicable, the Shelf
Registration Statement is declared effective but (A) thereafter ceases to be
effective or (B) ceases to be usable in connection with certain resales, in each
case (i) through (iv) upon the terms and conditions set forth in the
Registration Rights Agreement (each such event referred to in clauses (i)
through (iv), a "Registration Default"), then liquidated damages will be
assessed with respect to this Note at an amount of $0.05 per week per $1,000 of
Accreted Value of this Note (the "Liquidated Damages") for the 90-day period
immediately following the occurrence of the Registration Default, which amount
shall be increased by $0.05 per week per $1,000 of Accreted Value of this Note
at the beginning of each subsequent 90-day period (provided that such amount
shall not exceed $0.50 per week per $1,000 of Accreted Value of this Note in the
aggregate) and such amount shall be payable until such time (the "Step-Down
Date") as no Registration Default is in effect (after which such amount will be
restored to its initial amount). In no event shall the Company be required to
pay Liquidated Damages for more than one Registration Default at any given time.
Liquidated Damages shall be paid semi-annually on February 1 and August 1 in
each year; and the amount of Liquidated Damages shall be determined on the basis
of the number of days actually elapsed. Any unpaid Liquidated Damages on this
Note upon the issuance of an Exchange Note (as defined in the Indenture) in
exchange for this Note shall cease to be payable to the Holder hereof but such
Liquidated Damages shall be payable on the next February 1 or August 1 to the
Holder thereof.] The Company shall pay interest (including post-petition
interest in any proceeding under any Bankruptcy Law) on overdue Accreted Value
and premium [If Original Notes then insert: or Liquidated Damages], if any, at a
rate that is 1% per annum in excess of the then applicable rate of accretion of
the Notes, to the extent lawful.

                                       A-4

<PAGE>

        2.      Method of Payment. The Notes shall be payable as to Accreted
Value, premium or Liquidated Damages, if any, at the office or agency of the
Paying Agent and Registrar maintained for such purpose within the City and State
of New York, or, at the option of the Company, payment may be made by check
mailed to the Holders at their addresses set forth in the register of Holders,
provided that payment by wire transfer of immediately available funds will be
required with respect to Accreted Value of and premium, if any, on, all Global
Notes and all other Notes the Holders of which have provided wire transfer
instructions to the Company or the Paying Agent. Such payment shall be in such
coin or currency of the United States of America as at the time of payment is
legal tender for payment of public and private debts.

        3.      Paying Agent and Registrar. Initially, The Bank of New York,
the Trustee under the Indenture, shall act as Paying Agent and Registrar. The
Company may change any Paying Agent or Registrar without notice to any Holder.
The Company or any of its Subsidiaries may act in any such capacity.

        4.      Indenture. The Company issued the Notes under an Indenture
dated as of January 29, 2003 (the "Indenture") among the Company, the Guarantors
(from and after the consummation of the Escrow Corp. Merger) and the Trustee.
The terms of the Notes include those stated in the Indenture and those made part
of the Indenture by reference to the Trust Indenture Act of 1939, as amended (15
U.S. Code Sections 77aaa-77bbbb) (the "Trust Indenture Act"). The Notes are
subject to all such terms, and Holders are referred to the Indenture and such
Act for a statement of such terms. To the extent any provision of this Note
conflicts with the express provisions of the Indenture, the provisions of the
Indenture shall govern and be controlling. The Notes are obligations of the
Company. The Original Notes are limited to $808 million in aggregate principal
at maturity amount. Unless the context otherwise requires, the Original Notes
and the Exchange Notes shall constitute one series for all purposes under the
Indenture, including without limitation, amendments, waivers, redemptions and
Asset Sale Offers.

        5.      Optional Redemption. The Notes shall not be redeemable at the
Company's option prior to February 1, 2006. On or after February 1, 2006, the
Company may redeem all or a part of the Notes upon not less than 30 nor more
than 60 days' notice, at the redemption prices (expressed as percentages of
Accreted Value) set forth below plus Liquidated Damages, if any, on the Notes
redeemed, to the applicable redemption date, if redeemed during the twelve-month
period beginning on February 1 of the years indicated below:

                YEAR                                        PERCENTAGE
                ----                                        ----------
                2006....................................       106.125%
                2007....................................       103.063%
                2008 and thereafter.....................       100.000%

                                       A-5

<PAGE>

        6.      Mandatory Redemption.

        If the Escrow Corp. Merger has not occurred on or before the 60th day
after the Issue Date or, at the request of the Company prior to such date if the
Company in good faith reasonably determines that the conditions to the Escrow
Corp. Merger cannot be met, all and not less than all of the Notes then
outstanding shall be mandatorily redeemed by the Company within two Business
Days thereafter at a price equal to 101% of the Accreted Value of the Notes on
the date redeemed.

        Except as set forth in this paragraph 6, the Company shall not be
required to make mandatory redemption payments with respect to the Notes.

        7.      Repurchase at Option of Holder.

                (a)     If a Change of Control occurs, the Company shall make an
        offer (a "Change of Control Offer") to each Holder to repurchase all or
        any part (equal to $1,000 or an integral multiple thereof) of each
        Holder's Notes at a purchase price, in cash, equal to 101% of the
        Accreted Value of the Notes on the date of purchase plus Liquidated
        Damages, if any, on the Notes purchased, to the date of purchase (a
        "Change of Control Payment"). Within 15 days following any Change of
        Control, the Company shall mail a notice to each Holder setting forth
        the procedures governing the Change of Control Offer as required by the
        Indenture.

                (b)     When the aggregate amount of Excess Proceeds exceeds
        $10.0 million, the Company shall commence an offer to all Holders of
        Notes and all holders of other Indebtedness that is pari passu with the
        Notes containing provisions similar to those set forth in the Indenture
        with respect to offers to purchase or redeem with the proceeds of sales
        of assets (an "Asset Sale Offer") pursuant to Section 3.09 of the
        Indenture to purchase the maximum principal amount at maturity of Notes
        and such other pari passu Indebtedness that may be purchased out of the
        Excess Proceeds at an offer price in cash in an amount equal to 100% of
        the Accreted Value thereof, plus Liquidated Damages, if any, to the date
        of purchase, in accordance with the procedures set forth in the
        Indenture. To the extent that the aggregate amount of Notes tendered
        pursuant to an Asset Sale Offer is less than the Excess Proceeds, the
        remaining Excess Proceeds may be used for any purpose not otherwise
        prohibited by the Indenture. If the aggregate Accreted Value of Notes
        surrendered by Holders thereof, and the amounts due to any holders of
        any other debt of the Company entitled to receive a comparable asset
        sales offer, exceeds the amount of Excess Proceeds, the Trustee shall
        select the Notes and such other pari passu Indebtedness to be purchased
        on a pro rata basis. Holders of Notes that are the subject of an offer
        to purchase shall receive an Asset Sale Offer from the Company prior to
        any related purchase date and may elect to have such Notes purchased by
        completing the form entitled "Option of Holder to Elect Purchase" on the
        reverse of the Notes. [If not a Global Note, insert -- In the event of
        redemption or purchase pursuant to an Asset Sale Offer of this Note in
        part only, a new Note or Notes of like tenor for the unredeemed or

                                       A-6

<PAGE>

        unpurchased portion hereof shall be issued in the name of the Holder
        hereof upon the cancellation hereof.]

        8.      Notice of Redemption. Notice of redemption shall be mailed at
least 30 days but not more than 60 days before the redemption date to each
Holder whose Notes are to be redeemed at its registered address. Notes in
denominations larger than $1,000 may be redeemed in part but only in whole
multiples of $1,000, unless all of the Notes held by a Holder are to be
redeemed. On and after the redemption date, the Accreted Value of Notes or
portions thereof called for redemption ceases to increase.

        9.      Denominations, Transfer, Exchange. The Notes are in registered
form without coupons in denominations of $1,000 and integral multiples of
$1,000. The transfer of Notes may be registered and Notes may be exchanged as
provided in the Indenture. The Registrar and the Trustee may require a Holder,
among other things, to furnish appropriate endorsements and transfer documents
and the Company may require a Holder to pay any taxes and fees required by law
or permitted by the Indenture. The Company need not exchange or register the
transfer of any Note or portion of a Note selected for redemption, except for
the unredeemed portion of any Note being redeemed in part. Also, the Company
need not exchange or register the transfer of any Notes for a period of 15 days
before a selection of Notes to be redeemed or during the period between a record
date and the corresponding Interest Payment Date.

        10.     Persons Deemed Owners. The registered Holder of a Note may be
treated as its owner for all purposes.

        11.     Amendment, Supplement and Waiver. Subject to certain exceptions,
the Indenture, the Note Guarantees and the Notes may be amended or supplemented
with the consent of the Holders of at least a majority in aggregate principal at
maturity of the then outstanding Notes. Any existing default or non-compliance
with any provision of the Indenture, Note Guarantees or the Notes may be waived
with the consent of the Holders of a majority in aggregate principal at maturity
of the then outstanding Notes, voting as a single class. Without the consent of
any Holder of Notes, the Indenture, the Note Guarantees or the Notes may be
amended or supplemented to cure any ambiguity, defect or inconsistency, to
provide for uncertificated Notes in addition to or in place of certificated
Notes, to provide for the assumption of the Company's obligations to Holders of
the Notes in case of a merger or consolidation, to make any change that would
provide any additional rights or benefits to the Holders of the Notes or that
does not adversely affect the legal rights under the Indenture of any such
Holder, to comply with the requirements of the Securities and Exchange
Commission in order to effect or maintain the qualification of the Indenture
under the Trust Indenture Act or to conform the text of the Indenture, the Note
Guarantees or the Notes to any provision of the Description of Notes in the
Offering Circular to the extent that such provision in such Description of Notes
was intended to be a verbatim recitation of a provision of this Indenture, the
Note Guarantees or the Notes.

        12.     Defaults and Remedies. Events of Default include: (i) default
for 30 days in the payment when due of Liquidated Damages with respect to the
Notes, whether or not prohibited

                                       A-7

<PAGE>

by the subordination provisions of Article 11 of the Indenture; (ii) default in
payment when due of the Accreted Value of, or premium, if any, on the Notes,
whether or not prohibited by the subordination provisions of Article 11 of the
Indenture; (iii) failure by the Company to comply with the provisions of Article
5 of the Indenture or failure by the Company to consummate a Change of Control
Offer or Asset Sale Offer in accordance with the provisions of the Indenture;
(iv) failure by the Company or any of the Sister Guarantors for 30 days after
notice to comply with any of the other agreements in this Indenture or the
Notes; (v) default under any mortgage, indenture or instrument under which there
may be issued or by which there may be secured or evidenced any Indebtedness for
money borrowed by the Company or any of its Significant Subsidiaries (or the
payment of which is guaranteed by the Company or any of its Significant
Subsidiaries) whether such Indebtedness or Guarantee now exists, or is created
after the Issue Date, if that default: (a) is caused by a failure to pay
principal of, or interest or premium, if any, on such Indebtedness prior to the
expiration of the grace period provided in such Indebtedness on the date of such
default (a "Payment Default") or (b) results in the acceleration of such
Indebtedness prior to its express maturity, and, in each case, the principal
amount of any such Indebtedness, together with the principal amount of any other
such Indebtedness under which there has been a Payment Default or the maturity
of which has been so accelerated, aggregates $20.0 million or more; (vi) failure
by the Company or any of its Significant Subsidiaries to pay final judgments
aggregating in excess of $20.0 million, which judgments are not paid, discharged
or stayed for a period of 60 days; (vii) except as permitted by this Indenture,
any Note Guarantee by any Significant Subsidiary of the Company shall be held in
final and non-appealable judgment to be unenforceable or invalid or shall cease
for any reason to be in full force and effect or any such Guarantor that is a
Significant Subsidiary of the Company, or any Person acting on behalf of any
such Guarantor, shall in writing deny or disaffirm its obligations under its
Note Guarantee; (viii) failure by the Company to effect the mandatory redemption
of the Notes if required pursuant to Section 3.08 of the Indenture, and (ix)
certain events of bankruptcy or insolvency with respect to the Company or any of
its Significant Subsidiaries, or any group of Subsidiaries that, taken as a
whole, would constitute a Significant Subsidiary. If any Event of Default occurs
and is continuing, the Trustee or the Holders of at least 25% in principal
amount of the then outstanding Notes may declare all the Notes to be due and
payable in an amount equal to the Accreted Value of the Notes outstanding on the
date of acceleration. Notwithstanding the foregoing, in the case of an Event of
Default arising from certain events of bankruptcy or insolvency, all outstanding
Notes shall become due and payable without further action or notice. Holders may
not enforce the Indenture or the Notes except as provided in the Indenture.
Subject to certain limitations, Holders of a majority in principal amount of the
then outstanding Notes may direct the Trustee in its exercise of any trust or
power. The Trustee may withhold from Holders of the Notes notice of any
continuing Default or Event of Default (except a Default or Event of Default
relating to the payment of Accreted Value) if it determines that withholding
notice is in their interest. The Holders of a majority in aggregate principal at
maturity of the Notes then outstanding by notice to the Trustee may on behalf of
the Holders of all of the Notes waive any existing Default or Event of Default
and its consequences under the Indenture except a continuing Default or Event of
Default in the payment of Accreted Value of, and Liquidated Damages and premium,
if any, on the Notes. The Company is required to deliver to the Trustee annually
a statement regarding compliance with the Indenture, and the Company is

                                       A-8

<PAGE>

required, upon becoming aware of any Default or Event of Default, to deliver to
the Trustee a statement specifying such Default or Event of Default.

        13.     Subordination. Payment of Accreted Value, premium and
Liquidated Damages, if any, on the Notes is subordinated to the prior payment of
Senior Debt on the terms found in the Indenture.

        14.     Trustee Dealings with Company. The Trustee, in its individual
or any other capacity, may make loans to, accept deposits from, and perform
services for the Company or its Affiliates, and may otherwise deal with the
Company or its Affiliates, as if it were not the Trustee.

        15.     No Recourse Against Others. A director, officer, employee,
incorporator or stockholder of the Company or the Guarantors, as such, shall not
have any liability for any obligations of the Company or the Guarantors under
the Notes or the Indenture or for any claim based on, in respect of, or by
reason of, such obligations or their creation. Each Holder by accepting a Note
waives and releases all such liability. The waiver and release are part of the
consideration for the issuance of the Notes. In addition, prior to the
consummation of the Escrow Corp. Merger, the Holders of the Notes shall only
have recourse to Escrow Corp. under the Indenture and under the Notes and shall
not have any recourse to the stock or assets of the Parent or any of its
Affiliates or Subsidiaries (other than Escrow Corp.).

        16.     Authentication. This Note shall not be valid until authenticated
by the manual signature of the Trustee or an authenticating agent.

        17.     Abbreviations. Customary abbreviations may be used in the name
of a Holder or an assignee, such as: TEN COM (= tenants in common), TEN ENT (=
tenants by the entireties), JT TEN (= joint tenants with right of survivorship
and not as tenants in common), CUST (= Custodian), and U/G/M/A (= Uniform Gifts
to Minors Act).

        18.     Additional Rights of Holders of Restricted Global Notes and
Restricted Definitive Notes. In addition to the rights provided to the Holders
of Notes under the Indenture, Holders of Restricted Global Notes and Restricted
Definitive Notes shall have all the rights set forth in the Registration Rights
Agreement dated as of January 29, 2003, among the Company, the Guarantors (from
and after the consummation of the Escrow Corp. Merger) and the other parties
named on the signature pages thereof.

        19.     CUSIP Numbers. Pursuant to a recommendation promulgated by the
Committee on Uniform Security Identification Procedures, the Company has caused
CUSIP numbers to be printed on the Notes and the Trustee may use CUSIP numbers
in notices of redemption as a convenience to Holders. No representation is made
as to the accuracy of such numbers either as printed on the Notes or as
contained in any notice of redemption and reliance may be placed only on the
other identification numbers placed thereon.

                                       A-9

<PAGE>

        20.     Guarantees. From and after the consummation of the Escrow
Corp. Merger, this Note shall be entitled to the benefits of the Note Guarantees
made by the Guarantors under the Indenture. Additional Guarantors may be added
and Guarantors may be released from their Note Guarantees as provided in the
Indenture.

        The Company shall furnish to any Holder upon written request and without
charge a copy of the Indenture. Requests may be made to: American Tower
Corporation, 116 Huntington Avenue, Boston, MA 02116, Attention: Chief Financial
Officer and Secretary.

                                      A-10

<PAGE>

                                 ASSIGNMENT FORM

To assign this Note, fill in the form below:

(I) or (we) assign and transfer this Note to: __________________________________
                                                (Insert assignee's legal name)

                                   (Insert assignee's soc. sec. or tax I.D. no.)

                           (Print or type assignee's name, address and zip code)

and irrevocably appoint _________________________________ to transfer this Note
on the books of the Company. The agent may substitute another to act for him.

Date:
     ----------------

                  Your Signature:
                                 ------------------------------
                        (Sign exactly as your name appears on
                                 the face of this Note)

Signature Guarantee*:______________________

* Participant in a recognized Signature Guarantee Medallion Program (or other
signature guarantor acceptable to the Trustee).

                                      A-11

<PAGE>

                       OPTION OF HOLDER TO ELECT PURCHASE

If you want to elect to have this Note purchased by the Company pursuant to
Section 4.10 or 4.14 of the Indenture, check the appropriate box below:

       [_] Section 4.10                    [_] Section 4.14

If you want to elect to have only part of the Note purchased by the Company
pursuant to Section 4.10 or Section 4.14 of the Indenture, state the amount you
elect to have purchased:

                                  $____________

Date:
      -------------------

                   Your Signature:
                                  ---------------------------------
                         (Sign exactly as your name appears on
                                   the face of this Note)

                   Tax Identification No.:______________________

Signature Guarantee*:
                     ---------------------

* Participant in a recognized Signature Guarantee Medallion Program (or other
signature guarantor acceptable to the Trustee).

                                      A-12

<PAGE>

             SCHEDULE OF EXCHANGES OF INTERESTS IN THE GLOBAL NOTE*

The following exchanges of a part of this Global Note for an interest in another
Global Note or for a Definitive Note, or exchanges of a part of another Global
Note or Definitive Note for an interest in this Global Note, have been made:

<TABLE>
<CAPTION>
                                                                 PRINCIPAL AMOUNT OF
                                                                   THIS GLOBAL NOTE        SIGNATURE OF
                   AMOUNT OF DECREASE IN  AMOUNT OF DECREASE IN      FOLLOWING SUCH   AUTHORIZED OFFICER OF
                    PRINCIPAL AMOUNT OF    PRINCIPAL AMOUNT OF          DECREASE            TRUSTEE OR
DATE OF EXCHANGE      THIS GLOBAL NOTE       THIS GLOBAL NOTE         (OR INCREASE)          CUSTODIAN
----------------   ---------------------  ---------------------  -------------------  ---------------------
<S>                <C>                    <C>                    <C>                  <C>

</TABLE>

* This schedule should be included only if the Note is issued in global form.

                                      A-13

<PAGE>

                                                                       EXHIBIT B

                         FORM OF SUPPLEMENTAL INDENTURE

                    TO BE DELIVERED BY SUBSEQUENT GUARANTORS

        Supplemental Indenture (this "Supplemental Indenture"), dated as of
________, among __________________ (the "Guaranteeing Subsidiary"), a subsidiary
of AMERICAN TOWER ESCROW CORPORATION (or its permitted successor), a Delaware
corporation (the "Company"), the Company, the other Guarantors (as defined in
the Indenture referred to herein) and THE BANK OF NEW YORK, as trustee under the
Indenture referred to below (the "Trustee").

                               W I T N E S S E T H

        WHEREAS, the Company has heretofore executed and delivered to the
Trustee an indenture (the "Indenture"), dated as of January 29, 2003 providing
for the issuance of an aggregate principal amount of $808 Million of 12.25%
Senior Subordinated Discount Notes due 2008 (the "Notes");

        WHEREAS, the Indenture provides that under certain circumstances the
Guaranteeing Subsidiary shall execute and deliver to the Trustee a supplemental
indenture pursuant to which the Guaranteeing Subsidiary shall unconditionally
guarantee all of the Company's Obligations under the Notes and the Indenture
(the "Note Guarantee"); and

        WHEREAS, pursuant to Section 9.1 of the Indenture, the Trustee, the
Company and the other Guarantors are authorized to execute and deliver this
Supplemental Indenture.

        NOW THEREFORE, in consideration of the foregoing and for good and
valuable consideration, the receipt of which is hereby acknowledged, the
Guaranteeing Subsidiary, the Trustee, the Company and the other Guarantors
mutually covenant and agree for the equal and ratable benefit of the Holders of
the Notes as follows:

        1.      Capitalized Terms. Unless otherwise defined in this
Supplemental Indenture, capitalized terms used herein without definition shall
have the meanings assigned to them in the Indenture.

        2.      Agreement to be Bound; Guarantee. The Guaranteeing Subsidiary
hereby becomes a party to the Indenture as a Guarantor and as such will have all
of the rights and be subject to all of the obligations and agreements of a
Guarantor under the Indenture. The Guaranteeing Subsidiary hereby agrees to be
bound by all of the provisions of the Indenture applicable to a Guarantor and to
perform all of the obligations and agreements of a Guarantor under the
Indenture. In furtherance of the foregoing, the Guaranteeing Subsidiary shall be
deemed a Guarantor for purposes of Article 10 of the Indenture, including,
without limitation, Section 10.03 thereof.

<PAGE>

        3.      NEW YORK LAW TO GOVERN. THE INTERNAL LAW OF THE STATE OF NEW
YORK SHALL GOVERN AND BE USED TO CONSTRUE THIS SUPPLEMENTAL INDENTURE BUT
WITHOUT GIVING EFFECT TO APPLICABLE PRINCIPLES OF CONFLICTS OF LAW TO THE EXTENT
THAT THE APPLICATION OF THE LAWS OF ANOTHER JURISDICTION WOULD BE REQUIRED
THEREBY.

        4.      Counterparts.The parties may sign any number of copies of
this Supplemental Indenture. Each signed copy shall be an original, but all of
them together represent the same agreement.

        5.      Effect of Headings. The Section headings herein are for
convenience only and shall not affect the construction hereof.

        6.      The Trustee. The Trustee shall not be responsible in any
manner whatsoever for or in respect of the validity or sufficiency of this
Supplemental Indenture or for or in respect of the recitals contained herein,
all of which recitals are made solely by the Guaranteeing Subsidiary and the
Company.

        7.      Ratification of Indenture; Supplemental Indenture Part of
Indenture. Except as expressly amended hereby, the Indenture is in all respects
ratified and confirmed and all the terms, conditions and provisions thereof
shall remain in full force and effect. This Supplemental Indenture shall form a
part of the Indenture for all purposes, and every Holder of Notes heretofore or
hereafter authenticated and delivered shall by bound hereby.

                                       B-2

<PAGE>

        IN WITNESS WHEREOF, the parties hereto have caused this Supplemental
Indenture to be duly executed and attested, all as of the date first above
written.

                               [Guaranteeing Subsidiary]
                               By:
                                  ---------------------------------
                                  Name:
                                  Title:

                               American Tower Escrow Corporation
                               By:
                                  ---------------------------------
                                  Name:
                                  Title:

                               [Other Guarantors]
                               By:
                                  ---------------------------------
                                  Name:
                                  Title

                               The Bank of New York
                               as Trustee
                               By:
                                  ---------------------------------
                                  Name:
                                  Title:

                                       B-3

<PAGE>

                                                                       EXHIBIT C

                            [INTENTIONALLY OMITTED.]

                                       C-1

<PAGE>

                                                                       EXHIBIT D

                        FORM OF REGULATION S CERTIFICATE

        (For transfers pursuant to Section 2.06(a), (b)(iii), (d) and (e)
                                of the Indenture)

The Bank of New York,
as Trustee
101 Barclay St., 21W
New York, NY 10286
Attention: Corporate Trust Administration

                Re:    12.25% Senior Subordinated Discount Notes due 2008 of
                       American Tower Escrow Corporation (the "Notes")

        Reference is made to the Indenture, dated as of January 29, 2003 (the
"Indenture"), between American Tower Escrow Corporation, which is expected to
merge with and into American Towers, Inc. (the "Company"), the Guarantors named
therein and The Bank of New York, as Trustee. Terms used herein and defined in
the Indenture or in Regulation S or Rule 144 under the U.S. Securities Act of
1933, as amended (the "Securities Act") are used herein as so defined.

        This certificate relates to U.S. $____________ principal amount of
Notes, which are evidenced by the following certificate(s) (the "Specified
Notes"):

                CUSIP No(s). ___________________________

                CERTIFICATE No(s). _____________________

        The person in whose name this certificate is executed below (the
"Undersigned") hereby certifies that either (i) it is the sole beneficial owner
of the Specified Notes or (ii) it is acting on behalf of all the beneficial
owners of the Specified Notes and is duly authorized by them to do so. Such
beneficial owner or owners are referred to herein collectively as the "Owner".
If the Specified Notes are represented by a Global Notes, they are held through
the Depositary or a Participant in the name of the Undersigned, as or on behalf
of the Owner. If the Specified Notes are not represented by a Global Note, they
are registered in the name of the Undersigned, as or on behalf of the Owner.

        The Owner has requested that the Specified Notes be transferred to a
person (the "Transferee") who shall take delivery in the form of a Regulation S
Note. In connection with such transfer, the Owner hereby certifies that, unless
such transfer is being effected pursuant to an effective registration statement
under the Securities Act, it is being effected in accordance with Rule 904 or
Rule 144 under the Securities Act and with all applicable securities laws of the
states of the United States and other jurisdictions. Accordingly, the Owner
hereby further certifies as follows:

                                       D-1

<PAGE>

        (a)     Rule 904 Transfers. If the transfer is being effected in
accordance with Rule 904:

                (i)     the Owner is not a distributor of the Notes, an
                        affiliate of the Company or any such distributor or a
                        person acting on behalf of any of the foregoing;

                (ii)    the offer of the Specified Notes was not made to a
                        person in the United States;

                (iii)   either:

                        (1)     at the time the buy order was originated, the
                                Transferee was outside the United States or the
                                Owner and any person acting on its behalf
                                reasonably believed that the Transferee was
                                outside the United States, or

                        (2)     the transaction is being executed in, on or
                                through the facilities of the Eurobond market,
                                as regulated by the Association of International
                                Bond Dealers, or another designated offshore
                                securities market and neither the Owner nor any
                                person acting on its behalf knows that the
                                transaction has been prearranged with a buyer in
                                the United States;

                (iv)    no directed selling efforts have been made in the United
                        States by or on behalf of the Owner or any affiliate
                        thereof;

                (v)     if the Owner is a dealer in securities or has received a
                        selling concession, fee or other remuneration in respect
                        of the Specified Notes, and the transfer is to occur
                        during the Restricted Period, then the requirements of
                        Rule 904(c)(1)have been satisfied; and

                (vi)    the transaction is not part of a plan or scheme to evade
                        the registration requirements of the Securities Act.

        (b)     Rule 144 Transfers. If the transfer is being effected pursuant
to Rule 144:

                (i)     the transfer is occurring after a holding period of at
                        least one year (computed in accordance with paragraph
                        (d) of Rule 144) has elapsed since the Specified Notes
                        were last acquired from the Company or from an affiliate
                        of the Company, whichever is later, and is being
                        effected in accordance with the applicable amount,
                        manner of sale and notice requirements of Rule 144; or

                (ii)    the transfer is occurring after a holding period of at
                        least two years has elapsed since the Specified Notes
                        were last acquired from the Company or from an affiliate
                        of the Company, whichever is later, and the Owner is
                        not,

                                       D-2

<PAGE>

                        and during the preceding three months has not been, an
                        affiliate of the Company.

        This certificate and the statements contained herein are made for your
benefit and the benefit of the Company and the Purchasers.

        Dated:

                            ----------------------------------------------------
                            (Print the name of the Undersigned, as such term is
                            defined in the second paragraph of this
                            certificate.)

                            By:
                               -------------------------------------------------
                            Name:
                            Title:
                            (If the Undersigned is a corporation, partnership or
                            fiduciary, the title of the person signing on behalf
                            of the Undersigned must be stated.)

                                       D-3

<PAGE>

                                                                       EXHIBIT E

                      FORM OF RESTRICTED NOTES CERTIFICATE

        (For transfers pursuant to Section 2.06(a), (b)(iv), (d) and (e)
                                of the Indenture)

The Bank of New York,
as Trustee
101 Barclay St., 21W
New York, NY 10286
Attention: Corporate Trust Administration

                Re:    12.25% Senior Subordinated Discount Notes due 2008 of
                       American Tower Escrow Corporation (the "Notes")

        Reference is made to the Indenture, dated as of January 31, 2001 (the
"Indenture"), among American Tower Escrow Corporation, which is expected to
merge with and into American Towers, Inc. (the "Company"), the Guarantors named
therein and The Bank of New York, as Trustee. Terms used herein and defined in
the Indenture or in Regulation S or Rule 144 under the U.S. Securities Act of
1933, as amended (the "Securities Act") are used herein as so defined.

        This certificate relates to U.S. $_____________ principal amount of
Notes, which are evidenced by the following certificate(s) (the "Specified
Notes"):

                CUSIP No(s). ___________________________

                CERTIFICATE No(s). _____________________

        The person in whose name this certificate is executed below (the
"Undersigned") hereby certifies that either (i) it is the sole beneficial owner
of the Specified Notes or (ii) it is acting on behalf of all the beneficial
owners of the Specified Notes and is duly authorized by them to do so. Such
beneficial owner or owners are referred to herein collectively as the "Owner".
If the Specified Notes are represented by a Global Note, they are held through
the Depositary or a Participant in the name of the Undersigned, as or on behalf
of the Owner. If the Specified Notes are not represented by a Global Note, they
are registered in the name of the Undersigned, as or on behalf of the Owner.

        The Owner has requested that the Specified Notes be transferred to a
person (the "Transferee") who shall take delivery in the form of a Restricted
Note. In connection with such transfer, the Owner hereby certifies that, unless
such transfer is being effected pursuant to an effective registration statement
under the Securities Act, it is being effected in accordance with Rule 144A or
Rule 144 under the Securities Act and all applicable securities laws of the
states of the United States and other jurisdictions. Accordingly, the Owner
hereby further certifies as follows:

                                       E-1

<PAGE>

        (a)     Rule 144A Transfers. If the transfer is being effected in
accordance with Rule 144A:

                (i)     the Specified Notes are being transferred to a person
                        that the Owner and any person acting on its behalf
                        reasonably believe is a "qualified institutional buyer"
                        within the meaning of Rule 144A, acquiring for its own
                        account or for the account of a qualified institutional
                        buyer; and

                (ii)    the Owner and any person acting on its behalf have taken
                        reasonable steps to ensure that the Transferee is aware
                        that the Owner may be relying on Rule 144A in connection
                        with the transfer.

        (b)     Rule 144 Transfers. If the transfer is being effected pursuant
to Rule 144:

                (i)     the transfer is occurring after a holding period of at
                        least one year (computed in accordance with paragraph
                        (d) of Rule 144) has elapsed since the Specified Notes
                        were last acquired from the Company or from an affiliate
                        of the Company, whichever is later, and is being
                        effected in accordance with the applicable amount,
                        manner of sale and notice requirements of Rule 144; or

                (ii)    the transfer is occurring after a holding period of at
                        least two years has elapsed since the Specified Notes
                        were last acquired from the Company or from an affiliate
                        of the Company, whichever is later, and the Owner is
                        not, and during the preceding three months has not been,
                        an affiliate of the Company.

                                       E-2

<PAGE>

        This certificate and the statements contained herein are made for your
benefit and the benefit of the Company and the Purchasers.

        Dated:

                            ----------------------------------------------------
                            (Print the name of the Undersigned,
                            as such term is defined in the
                            second paragraph of this certificate.)

                            By:
                               -------------------------------------------------
                            Name:
                            Title:
                            (If the Undersigned is a corporation, partnership or
                            fiduciary, the title of the person signing on behalf
                            of the Undersigned must be stated.)

                                       E-3

<PAGE>

                                                                       EXHIBIT F

                     FORM OF UNRESTRICTED NOTES CERTIFICATE

     (For removal of Securities Act Legends pursuant to Section 2.06(f)(ii)
                                of the Indenture)

The Bank of New York,
as Trustee
101 Barclay St., 21W
New York, NY 10286
Attention:  Corporate Trust Administration

                Re:    12.25% Senior Subordinated Discount Notes due 2008 of
                       American Tower Escrow Corporation (the "Notes")

        Reference is made to the Indenture, dated as of January 29, 2003 (the
"Indenture"), between American Tower Escrow Corporation, which is expected to
merge with and into American Towers, Inc. (the "Company"), the Guarantors named
therein and The Bank of New York, as Trustee. Terms used herein and defined in
the Indenture or in Regulation S or Rule 144 under the U.S. Securities Act of
1933, as amended (the "Securities Act") are used herein as so defined.

        This certificate relates to U.S. $_____________ principal amount of
Notes, which are evidenced by the following certificate(s) (the "Specified
Notes"):

                CUSIP No(s). ___________________________

                CERTIFICATE No(s). _____________________

        The person in whose name this certificate is executed below (the
"Undersigned") hereby certifies that either (i) it is the sole beneficial owner
of the Specified Notes or (ii) it is acting on behalf of all the beneficial
owners of the Specified Notes and is duly authorized by them to do so. Such
beneficial owner or owners are referred to herein collectively as the "Owner".
If the Specified Notes are represented by a Global Note, they are held through
the Depositary or a Participant in the name of the Undersigned, as or on behalf
of the Owner. If the Specified Notes are not represented by a Global Note, they
are registered in the name of the Undersigned, as or on behalf of the Owner.

        The Owner has requested that the Specified Notes be exchanged for Notes
bearing no Securities Act Legend pursuant to Section 305(c) of the Indenture. In
connection with such exchange, the Owner hereby certifies that the exchange is
occurring after a holding period of at least two years (computed in accordance
with paragraph (d) of Rule 144) has elapsed since the Specified Notes were last
acquired from the Company or from an affiliate of the Company, whichever is
later, and the Owner is not, and during the preceding three months has not been,
an affiliate of the Company. The Owner also acknowledges that any future
transfers of the

                                       F-1

<PAGE>

Specified Notes must comply with all applicable securities laws of the states of
the United States and other jurisdictions.

        This certificate and the statements contained herein are made for your
benefit and the benefit of the Company and the Purchasers.

        Dated:

                            ----------------------------------------------------
                            (Print the name of the Undersigned, as such
                            term is defined in the second paragraph of this
                            certificate.)

                            By:
                               -------------------------------------------------
                            Name:
                            Title:
                            (If the Undersigned is a corporation, partnership or
                            fiduciary, the title of the person signing on behalf
                            of the Undersigned must be stated.)

                                       F-2<PAGE>

                                                                     Exhibit 4.6

================================================================================

                           American Tower Corporation

                              Warrants to Purchase
                        11,389,012 Shares of Common Stock

                                Warrant Agreement

                          Dated as of January 29, 2003

                              The Bank of New York

                                  Warrant Agent

================================================================================

<PAGE>

               WARRANT AGREEMENT, dated as of January 29, 2003, between American
Tower Corporation, a Delaware corporation (the "Company"), and The Bank of New
York, a New York banking corporation, as warrant agent (the "Warrant Agent").

               WHEREAS, the Company proposes to issue warrants (the "Warrants")
to initially purchase up to an aggregate of 11,389,012 shares of Class A Common
Stock, par value $0.01 per share (the "Common Stock"), of the Company (the
Common Stock issuable on exercise of the Warrants being referred to herein as
the "Warrant Shares"), in connection with the offering (the "Offering") by
American Tower Escrow Corporation ("Escrow Corp."), a Delaware corporation,
which is expected to subsequently merge with and into American Towers, Inc., a
Delaware Corporation ("ATI"), of 808,000 Units (the "Units"), each consisting of
$1,000 principal amount at maturity of Escrow Corp.'s 12.25% Senior Subordinated
Discount Notes due 2008 (the "Notes") and one Warrant, each Warrant initially
representing the right to purchase 14.0953 Warrant Shares at the Exercise Price
(as defined herein). The Notes are to be issued under an indenture (the
"Indenture") among the Company, the Guarantors named therein (from and after the
consummation of the Escrow Corp. Merger (as defined herein)) and The Bank of New
York, as trustee (the "Trustee"), dated the date hereof, on a private placement
basis pursuant to an exemption under Section 4(2) of the United States
Securities Act of 1933, as amended.

               WHEREAS, the Company desires the Warrant Agent to act on behalf
of the Company, and the Warrant Agent is willing so to act in connection with
the issuance of Warrant Certificates (as defined) and other matters as provided
herein.

               NOW, THEREFORE, in consideration of the premises and the mutual
agreements herein set forth, the parties hereto agree as follows:

SECTION 1.     CERTAIN DEFINITIONS.

               As used in this Agreement, the following terms shall have the
following respective meanings:

               "144A Global Warrant" means a global Warrant substantially in the
form of Exhibit A hereto bearing the Global Warrant Legend and the Private
Placement Legend and deposited with or on behalf of, and registered in the name
of, the Depositary or its nominee.

               "Affiliate" of any specified Person means any other Person
directly or indirectly controlling or controlled by or under direct or indirect
common control with such specified Person. For purposes of this definition,
"control," as used with respect to any Person, means the possession, directly or
indirectly, of the power to direct or cause the direction of the management or
policies of such Person, whether through the ownership of voting securities, by
agreement or otherwise; provided that beneficial ownership of 10% or more of the
Voting Stock of a Person will be deemed to be control. No natural person who is
an executive officer or director of a Person shall, solely by virtue of such
position, be deemed to control such Person.

               "Applicable Procedures" means, with respect to any transfer or
exchange of or for beneficial interests in any Global Warrant, the rules and
procedures of the Depositary, Euroclear and Clearstream that apply to such
transfer or exchange.

               "Business Day" means any day other than a Legal Holiday.

               "Clearstream" means Clearstream Banking, S.A.

                                        1

<PAGE>

               "Closing Date" means the date hereof.

               "Commission" means the Securities and Exchange Commission.

               "Definitive Warrant" means a certificated Warrant registered in
the name of the Holder thereof and issued in accordance with Section 3.5 hereof,
substantially in the form of Exhibit A hereto except that such Warrant shall not
bear the Global Warrant Legend and shall not have the "Schedule of Exchanges of
Interests in the Global Warrant" attached thereto.

               "Depositary" means, with respect to the Warrants issuable or
issued in whole or in part in global form, the Person specified in Section 3.3
hereof as the Depositary with respect to the Warrants, and any and all
successors thereto appointed as Depositary hereunder and having become such
pursuant to the applicable provision of the Indenture.

               "Disinterested Director" means, in connection with any issuance
of securities that gives rise to a determination of the Fair Value thereof, each
member of the Board of Directors of the Company who is not an officer, employee,
director or other affiliate of the party to whom the Company is proposing to
issue the securities giving rise to such determination.

               "Escrow Corp. Merger" means the merger transaction involving
Escrow Corp., a Delaware corporation, and ATI pursuant to the Escrow Corp.
Merger Agreement.

               "Escrow Corp. Merger Agreement" means that certain Agreement and
Plan of Merger dated as of January 29, 2003 by and between Escrow Corp. and ATI
pursuant to which Escrow Corp. is expected to merge with and into ATI.

               "Euroclear" means Euroclear Bank S.A./N.V., as operator of the
Euroclear system.

               "Exchange Act" means the Securities Exchange Act of 1934, as
amended.

               "Exercise Period" has the meaning assigned to it in Section 4(a)
hereof.

               "Exercise Price" means the Initial Exercise Price subject to the
conditions and adjustments described in this Warrant Agreement.

               "Fair Value" per security at any date of determination shall be
(1) in connection with a sale to a party that is not an affiliate of the Company
in an arm's-length transaction (a "Non-Affiliate Sale"), the price per security
at which such security is sold and (2) in connection with any sale to an
affiliate of the Company, (a) the last price per security at which such security
was sold in a Non-Affiliate Sale within the three-month period preceding such
date of determination or (b) if clause (a) is not applicable, the fair market
value of such security determined in good faith by (i) a majority of the Board
of Directors of the Company, including a majority of the disinterested
directors, and approved in a board resolution delivered to the Warrant Agent or
(ii) a nationally recognized investment banking, appraisal or valuation firm,
which is not an affiliate of the Company, in each case taking into account,
among all other factors deemed relevant by the Board of Directors or such
investment banking, appraisal or valuation firm, the trading price and volume of
such security on any national securities exchange or automated quotation system
on which such security is traded.

                                        2

<PAGE>

               "Global Warrants" means, individually and collectively, each of
the Restricted Global Warrants and the Unrestricted Global Warrants,
substantially in the form of Exhibit A hereto issued in accordance with Section
3.1(b) and 3.5 hereof.

               "Global Warrant Legend" means the legend set forth in Section
3.5(g)(ii), which is required to be placed on all Global Warrants issued under
this Warrant Agreement.

               "Holder" means a person who is listed as the record owner of
Registrable Securities.

               "IAI Global Warrant" means the global Warrant substantially in
the form of Exhibit A hereto bearing the Global Warrant Legend and the Private
Placement Legend and deposited with or on behalf of and registered in the name
of the Depositary or its nominee.

               "Indenture" has the meaning assigned to it in the recitals to
this Agreement.

               "Initial Exercise Price" means $0.01 per Warrant Share.

               "Indirect Participant" means a Person who holds a beneficial
interest in a Global Warrant through a Participant.

               "Initial Purchasers" means Credit Suisse First Boston LLC and
Goldman, Sachs & Co.

               "Institutional Accredited Investor" means an institution that is
an "accredited investor" as defined in Rule 501(a)(1), (2), (3) or (7) under the
Securities Act, which is not also a QIB.

               "Legal Holiday" means a Saturday, a Sunday or a day on which
banking institutions in the City of New York, the City of Boston or the city in
which the principal corporate trust office or the Warrant Agent is located or at
a place of payment are authorized by law, regulation or executive order to
remain closed. If a payment date is a Legal Holiday at a place of payment,
payment may be made at that place on the next succeeding day that is not a Legal
Holiday, and no interest shall accrue on such payment for the intervening
period.

               "Market Value" means the value per share of the Company's Class A
Common Stock, par value $0.01 per share, as of any date, which shall equal (i)
if such Common Stock is primarily traded on a securities exchange, the last sale
price on such securities exchange on the trading day immediately prior to the
date of determination, or if no sale occurred on such day, the mean between the
closing "bid" and "asked" prices on such day, (ii) if the principal market for
such Common Stock is in the over-the-counter market, the closing sale price on
the trading day immediately prior to the date of the determination, as published
by the National Association of Securities Dealers Automated quotation System or
similar organization, or if such price is not so published on such day, the mean
between the closing "bid" and "asked" prices, if available, on such day, which
prices may be obtained from any reputable pricing service, broker or dealer, and
(iii) if neither clause (i) nor clause (ii) is applicable, the fair market value
on the date of determination of such Common Stock as determined in good faith by
the board of directors of the Company.

               "Non-U.S. Person" means a Person who is not a U.S. Person.

               "Notes" has the meaning assigned to it in the recitals to this
Agreement.

                                        3

<PAGE>

               "Officer" means, with respect to any Person, the Chairman of the
Board, the Chief Executive Officer, the President, the Chief Operating Officer,
the Chief Financial Officer, the Treasurer, any Assistant Treasurer, the
Controller, the Secretary or any Senior or Executive Vice-President of such
Person.

               "Opinion of Counsel" means an opinion from legal counsel. The
counsel may be an employee of or counsel to the Company or any subsidiary of the
Company.

               "Participant" means, with respect to the Depositary, Euroclear or
Clearstream, a Person who has an account with the Depositary, Euroclear or
Clearstream, respectively (and, with respect to The Depository Trust Company,
shall include Euroclear and Clearstream).

               "Person" means any individual, corporation, partnership, joint
venture, association, joint-stock company, trust, unincorporated organization,
limited liability company or government or other entity.

               "Private Placement Legend" means the legend set forth in Section
3.5(g)(i) to be placed on all Warrants issued under this Warrant Agreement
except where otherwise permitted by the provisions of this Warrant Agreement.

               "QIB" means a "qualified institutional buyer" as defined in Rule
144A.

               "Registrable Securities" shall mean the Warrants, the Warrant
Shares and any other securities issued or issuable with respect to the Warrants
or the Warrant Shares by way of a stock dividend or stock split or in connection
with a combination of shares, recapitalization, merger, consolidation or other
reorganization; provided that a security ceases to be a Registrable Security
when it is no longer a Transfer Restricted Security. The Registrable Securities
are entitled to the benefits of the Warrant Registration Rights Agreement.

               "Registration Statement" means the Registration Statement as
defined in the Warrant Registration Rights Agreement.

               "Regulation S" means Regulation S promulgated under the
Securities Act.

               "Regulation S Global Warrant" means a global Warrant in the form
of Exhibit A hereto bearing the Global Warrant Legend, the Private Placement
Legend and the Regulation S Legend and deposited with or on behalf of and
registered in the name of the Depositary or its nominee.

               "Regulation S Legend" means the legend set forth in Section
3.5(g)(iv) to be placed on all Registrable Securities issued pursuant to
Regulation S.

               "Restricted Definitive Warrant" means a Definitive Warrant
bearing the Private Placement Legend.

               "Restricted Global Warrant" means a Global Warrant bearing the
Private Placement Legend.

               "Restricted Period" means the one-year distribution compliance
period as defined in Regulation S.

                                        4

<PAGE>

               "Rule 144" means Rule 144 promulgated under the Securities Act.

               "Rule 144A" means Rule 144A promulgated under the Securities Act.

               "Rule 903" means Rule 903 promulgated under the Securities Act.

               "Rule 904" means Rule 904 promulgated under the Securities Act.

               "Securities Act" means the Securities Act of 1933, as amended.

               "Separation Date" means the earliest to occur of (i) 180 days
after the closing of the Offering, (ii) the date on which a registration
statement with respect to a registered exchange offer for the Notes is declared
effective under the Securities Act, (iii) the date a shelf registration
statement with respect to the Warrants is declared effective under the
Securities Act, (iv) such date as Credit Suisse First Boston LLC in its sole
discretion shall determine and (v) in the event of Change of Control (as defined
in the Indenture), the date the Company mails the requisite notice to the
holders.

               "Transfer Agent" shall have the meaning assigned to it in Section
6(b) hereof.

               "Transfer Restricted Securities" means (a) each Warrant and
Warrant Share held by an Affiliate of the Company and (b) each other Warrant and
Warrant Share until the earlier to occur of (i) the date on which such Warrant
or Warrant Share (other than any Warrant Share issued upon exercise of a Warrant
in accordance with a Registration Statement (as defined in the Warrant
Registration Rights Agreement) has been disposed of in accordance with a
Registration Statement and (ii) the date on which such Warrant or Warrant Share
(or the related Warrant) is distributed to the public pursuant to Rule 144 under
the Act.

               "Trustee" has the meaning assigned to it in the recitals to this
Agreement.

               "Unrestricted Global Warrant" means a global Warrant
substantially in the form of Exhibit A attached hereto that bears the Global
Warrant Legend and that has the "Schedule of Exchanges of Interests in the
Global Warrant" attached thereto, and that is deposited with or on behalf of and
registered in the name of the Depositary, representing a series of Warrants that
do not bear the Private Placement Legend.

               "Unrestricted Definitive Warrant" means one or more Definitive
Warrants that do not bear and are not required to bear the Private Placement
Legend.

               "U.S. Person" means a U.S. person as defined in Rule 902(o) under
the Securities Act.

               "Warrants" has the meaning assigned to it in the recitals to this
Agreement.

               "Warrant Certificates" shall have the meaning assigned to it in
Section 3.1(a) hereof.

               "Warrant Registration Rights Agreement" means the registration
rights agreement, dated as of January 29, 2003, between the Company and the
Initial Purchasers relating to the Warrants and the Warrant Shares.

               "Warrant Shares" has the meaning assigned to it in the recitals
to this Agreement.

                                        5

<PAGE>

SECTION 2.     APPOINTMENT OF WARRANT AGENT.

               The Company hereby appoints the Warrant Agent to act as agent for
the Company in accordance with the instructions set forth hereinafter in this
Agreement and the Warrant Agent hereby accepts such appointment.

SECTION 3.     ISSUANCE OF WARRANTS; WARRANT CERTIFICATES.

        3.1.   FORM AND DATING.

               (a)  General.

               The Warrants shall be substantially in the form of Exhibit A
hereto (the "Warrant Certificates"). The Warrants may have notations, legends or
endorsements required by law, stock exchange rule or usage. Each Warrant shall
be dated the date of the countersignature.

               The terms and provisions contained in the Warrants shall
constitute, and are hereby expressly made, a part of this Warrant Agreement. The
Company and the Warrant Agent, by their execution and delivery of this Warrant
Agreement, expressly agree to such terms and provisions and to be bound thereby.
However, to the extent any provision of any Warrant conflicts with the express
provisions of this Warrant Agreement, the provisions of this Warrant Agreement
shall govern and be controlling.

               (b)  Global Warrants.

               Warrants issued in global form shall be substantially in the form
of Exhibit A attached hereto (including the Global Warrant Legend thereon and
the "Schedule of Exchanges of Interests in the Global Warrant" attached
thereto). Warrants issued in definitive form shall be substantially in the form
of Exhibit A attached hereto (but without the Global Warrant Legend thereon and
without the "Schedule of Exchanges of Interests in the Global Warrant" attached
thereto). Each Global Warrant shall represent such of the outstanding Warrants
as shall be specified therein and each shall provide that it shall represent the
number of outstanding Warrants from time to time endorsed thereon and that the
number of outstanding Warrants represented thereby may from time to time be
reduced or increased, as appropriate, to reflect exchanges and redemptions. Any
endorsement of a Global Warrant to reflect the amount of any increase or
decrease in the number of outstanding Warrants represented thereby shall be made
by the Warrant Agent in accordance with instructions given by the Holder thereof
as required by Section 3.5 hereof.

               (c)  Euroclear and Clearstream Procedures Applicable.

               The provisions of the "Operating Procedures of the Euroclear
System" and "Terms and Conditions Governing Use of Euroclear" and the "General
Terms and Conditions of Clearstream Banking" and "Customer Handbook" of
Clearstream will be applicable to transfers of beneficial interests in the
Regulation S Global Warrants that are held by Participants through Euroclear or
Clearsteam.

        3.2.   EXECUTION.

               An Officer shall sign the Warrants for the Company by manual or
facsimile signature.

               If the Officer whose signature is on a Warrant no longer holds
that office at the time a Warrant is countersigned, the Warrant shall
nevertheless be valid.

                                        6

<PAGE>

               A Warrant shall not be valid until countersigned by the manual
signature of the Warrant Agent. The signature (which may be a facsimile) shall
be conclusive evidence that the Warrant has been properly issued under this
Warrant Agreement.

               The Warrant Agent shall, upon a written order of the Company
signed by an Officer (a "Warrant Countersignature Order"), countersign Warrants
for original issue up to the number stated in the preamble hereto.

               The Warrant Agent may appoint an agent acceptable to the Company
to countersign Warrants. Such an agent may countersign Warrants whenever the
Warrant Agent may do so. Each reference in this Warrant Agreement to a
countersignature by the Warrant Agent includes a countersignature by such agent.
Such an agent has the same rights as the Warrant Agent to deal with Holders, the
Company or an Affiliate of the Company.

        3.3.   WARRANT REGISTRAR.

               The Company shall maintain an office or agency where Warrants may
be presented for registration of transfer or for exchange ("Warrant Registrar").
The Warrant Registrar shall keep a register of the Warrants and of their
transfer and exchange. The Company may appoint one or more co-Warrant
Registrars. The term "Warrant Registrar" includes any co-Warrant Registrar. The
Company may change any Warrant Registrar without notice to any holder. The
Company shall notify the Warrant Agent in writing of the name and address of any
agent not a party to this Warrant Agreement. If the Company fails to appoint or
maintain another entity as Warrant Registrar, the Warrant Agent shall act as
such. The Company or any of its subsidiaries may act as Warrant Registrar.

               The Company initially appoints The Depository Trust Company
("DTC") to act as Depositary with respect to the Global Warrants.

               The Company initially appoints the Warrant Agent to act as the
Warrant Registrar with respect to the Global Warrants.

        3.4.   HOLDER LISTS.

               The Warrant Agent shall preserve in as current a form as is
reasonably practicable the most recent list available to it of the names and
addresses of all Holders. If the Warrant Agent is not the Warrant Registrar, the
Company shall promptly furnish to the Warrant Agent at such times as the Warrant
Agent may request in writing, a list in such form and as of such date as the
Warrant Agent may reasonably require of the names and addresses of the Holders.

        3.5.   TRANSFER AND EXCHANGE.

        (a)    Transfer and Exchange of Global Warrants.

               A Global Warrant may not be transferred as a whole except by the
Depositary to a nominee of the Depositary, by a nominee of the Depositary to the
Depositary or to another nominee of the Depositary, or by the Depositary or any
such nominee to a successor Depositary or a nominee of such successor
Depositary. All Global Warrants will be exchanged by the Company for Definitive
Warrants if (i) the Company delivers to the Warrant Agent notice from the
Depositary that it is unwilling or unable to continue to act as Depositary or
that it is no longer a clearing agency registered under the Exchange Act and, in
either case, a successor Depositary is not appointed by the Company within 120
days after the date

                                        7

<PAGE>

of such notice from the Depositary; (ii) in the case of a Global Warrant held
for an account of Euroclear or Clearstream, Euroclear or Clearstream, as the
case may be, (a) is closed for business for a continuous period of 14 days
(other than by reason of statutory or other holidays), or (b) announces an
intention permanently to cease business or does in fact do so; or (iii) the
Company in its sole discretion determines that the Global Warrants (in whole but
not in part) should be exchanged for Definitive Warrants and delivers a written
notice to such effect to the Warrant Agent. Upon the occurrence of any of the
preceding events in (i), (ii) or (iii) above, Definitive Warrants shall be
issued in such names as the Depositary shall instruct the Warrant Agent. Global
Warrants also may be exchanged or replaced, in whole or in part, as provided in
Sections 3.6 and 3.7 hereof. A Global Warrant may not be exchanged for another
Warrant other than as provided in this Section 3.5(a), however, beneficial
interests in a Global Warrant may be transferred and exchanged as provided in
Section 3.5(b), (c) or (f) hereof.

        (b)    Transfer and Exchange of Beneficial Interests in the Global
               Warrants.

               The transfer and exchange of beneficial interests in the Global
Warrants shall be effected through the Depositary, in accordance with the
provisions of this Warrant Agreement and the Applicable Procedures. Beneficial
interests in the Restricted Global Warrants shall be subject to restrictions on
transfer comparable to those set forth herein to the extent required by the
Securities Act. Transfers of beneficial interests in the Global Warrants also
shall require compliance with either subparagraph (i) or (ii) below, as
applicable, as well as one or more of the other following subparagraphs, as
applicable:

               (i) Transfer of Beneficial Interests in the Same Global Warrant.
        Beneficial interests in any Restricted Global Warrant may be transferred
        to Persons who take delivery thereof in the form of a beneficial
        interest in the same Restricted Global Warrant in accordance with the
        transfer restrictions set forth in the Private Placement Legend;
        provided, however, that prior to the expiration of the Restricted
        Period, transfers of beneficial interests in the Regulation S Global
        Warrant may not be made to a U.S. Person or for the account or benefit
        of a U.S. Person (other than the Initial Purchaser). Beneficial
        interests in any Unrestricted Global Warrant may be transferred to
        Persons who take delivery thereof in the form of a beneficial interest
        in an Unrestricted Global Warrant. No written orders or instructions
        shall be required to be delivered to the Warrant Registrar to effect the
        transfers described in this Section 3.5(b)(i).

               (ii) All Other Transfers and Exchanges of Beneficial Interests in
        Global Warrants. In connection with all transfers and exchanges of
        beneficial interests that are not subject to Section 3.5(b)(i) above,
        the transferor of such beneficial interest must deliver to the Warrant
        Registrar either (A) both (1) a written order from a Participant or an
        Indirect Participant given to the Depositary in accordance with the
        Applicable Procedures directing the Depositary to credit or cause to be
        credited a beneficial interest in another Global Warrant in an amount
        equal to the beneficial interest to be transferred or exchanged and (2)
        instructions given in accordance with the Applicable Procedures
        containing information regarding the Participant account to be credited
        with such increase or (B) both (1) a written order from a Participant or
        an Indirect Participant given to the Depositary in accordance with the
        Applicable Procedures directing the Depositary to cause to be issued a
        Definitive Warrant in an amount equal to the beneficial interest to be
        transferred or exchanged and (2) instructions given by the Depositary to
        the Warrant Registrar containing information regarding the Person in
        whose name such Definitive Warrant shall be registered to effect the
        transfer or exchange referred to in (1) above. Upon effectiveness of the
        Registration Statement (as defined in the Warrant Registration Rights
        Agreement) by the Company in accordance with Section 3.5(f) hereof, the
        requirements of this Section 3.5(b)(ii) shall be deemed to have been
        satisfied upon receipt by the Warrant Registrar of a certification
        required by the Company in connection with such Registration Statement
        delivered by the Holder

                                        8

<PAGE>

        of such beneficial interests in the Restricted Global Warrants. Upon
        satisfaction of all of the requirements for transfer or exchange of
        beneficial interests in Global Warrants contained in this Agreement and
        the Warrants or otherwise applicable under the Securities Act, the
        Warrant Agent shall adjust the principal amount of the relevant Global
        Warrant(s) pursuant to Section 3.5(h) hereof.

               (iii) Transfer of Beneficial Interests to Another Restricted
        Global Warrant. A beneficial interest in any Restricted Global Warrant
        may be transferred to a Person who takes delivery thereof in the form of
        a beneficial interest in another Restricted Global Warrant if the
        transfer complies with the requirements of Section 3.5(b)(ii) above and
        the Warrant Registrar receives the following:

                    (A) if the transferee will take delivery in the form of a
               beneficial interest in the 144A Global Warrant, then the
               transferor must deliver a certificate in the form of Exhibit B
               hereto, including the certifications in item (1) thereof;

                    (B) if the transferee will take delivery in the form of a
               beneficial interest in the Regulation S Global Warrant, then the
               transferor must deliver a certificate in the form of Exhibit B
               hereto, including the certifications in item (2) thereof; and

                    (C) if the transferee will take delivery in the form of a
               beneficial interest in the IAI Global Warrant, then the
               transferor must deliver a certificate in the form of Exhibit B
               hereto, including the certifications and certificates and Opinion
               of Counsel required by item (3) thereof, if applicable.

               (iv) Transfer and Exchange of Beneficial Interests in a
        Restricted Global Warrant for Beneficial Interests in the Unrestricted
        Global Warrant. A beneficial interest in any Restricted Global Warrant
        may be exchanged by any holder thereof for a beneficial interest in an
        Unrestricted Global Warrant or transferred to a Person who takes
        delivery thereof in the form of a beneficial interest in an Unrestricted
        Global Warrant if the exchange or transfer complies with the
        requirements of Section 3.5(b)(ii) above and:

                    (A) such transfer is effected pursuant to the Registration
               Statement in accordance with the Warrant Registration Rights
               Agreement; or

                    (B) the Warrant Registrar receives the following:

                         (1) if the holder of such beneficial interest in a
                    Restricted Global Warrant proposes to exchange such
                    beneficial interest for a beneficial interest in an
                    Unrestricted Global Warrant, a certificate from such holder
                    in the form of Exhibit C hereto, including the
                    certifications in item (1)(a) thereof; or

                         (2) if the holder of such beneficial interest in a
                    Restricted Global Warrant proposes to transfer such
                    beneficial interest to a Person who shall take delivery
                    thereof in the form of a beneficial interest in an
                    Unrestricted Global Warrant, a certificate from such holder
                    in the form of Exhibit B hereto, including the
                    certifications in item (4) thereof;

        and, in each such case set forth in this subparagraph (B), if the
        Warrant Registrar so requests or if the Applicable Procedures so
        require, an Opinion of Counsel in form reasonably acceptable to the

                                        9

<PAGE>

        Warrant Registrar to the effect that such exchange or transfer is in
        compliance with the Securities Act and that the restrictions on transfer
        contained herein and in the Private Placement Legend are no longer
        required in order to maintain compliance with the Securities Act.

               If any such transfer is effected pursuant to subparagraph (B)
above at a time when an Unrestricted Global Warrant has not yet been issued, the
Company shall issue and, upon receipt of an Warrant Countersignature Order in
accordance with Section 3.2 hereof, the Warrant Agent shall countersign one or
more Unrestricted Global Warrants in the number equal to the number of
beneficial interests transferred pursuant to subparagraph (B) above.

               Beneficial interests in an Unrestricted Global Warrant cannot be
exchanged for, or transferred to Persons who take delivery thereof in the form
of, a beneficial interest in a Restricted Global Warrant.

        (c)    Transfer and Exchange of Beneficial Interests for Definitive
               Warrants.

               (i)  Beneficial Interests in Restricted Global Warrants to
        Restricted Definitive Warrants. If any holder of a beneficial interest
        in a Restricted Global Warrant proposes to exchange such beneficial
        interest for a Restricted Definitive Warrant or to transfer such
        beneficial interest to a Person who takes delivery thereof in the form
        of a Restricted Definitive Warrant, then, upon receipt by the Warrant
        Registrar of the following documentation:

                    (A) if the holder of such beneficial interest in a
               Restricted Global Warrant proposes to exchange such beneficial
               interest for a Restricted Definitive Warrant, a certificate from
               such holder in the form of Exhibit C hereto, including the
               certifications in item (2)(a) thereof;

                    (B) if such beneficial interest is being transferred to a
               QIB in accordance with Rule 144A, a certificate to the effect set
               forth in Exhibit B hereto, including the certifications in item
               (1) thereof;

                    (C) if such beneficial interest is being transferred to a
               Non-U.S. Person in an offshore transaction in accordance with
               Rule 903 or Rule 904 under the Securities Act, a certificate to
               the effect set forth in Exhibit B hereto, including the
               certifications in item (2) thereof;

                    (D) if such beneficial interest is being transferred
               pursuant to an exemption from the registration requirements of
               the Securities Act in accordance with Rule 144, a certificate to
               the effect set forth in Exhibit B hereto, including the
               certifications in item (3)(a) thereof;

                    (E) if such beneficial interest is being transferred to an
               Institutional Accredited Investor in reliance on an exemption
               from the registration requirements of the Securities Act other
               than those listed in subparagraphs (B) through (D) above, a
               certificate to the effect set forth in Exhibit B hereto,
               including the certifications, certificates and Opinion of Counsel
               required by item (3) thereof, if applicable;

                    (F) if such beneficial interest is being transferred to the
               Company or any of its Subsidiaries, a certificate to the effect
               set forth in Exhibit B hereto, including the certifications in
               item (3)(b) thereof; or

                                       10

<PAGE>

                    (G) if such beneficial interest is being transferred
               pursuant to an effective registration statement under the
               Securities Act, a certificate to the effect set forth in Exhibit
               B hereto, including the certifications in item (3)(c) thereof,

the Warrant Agent shall cause, in accordance with the standing instructions and
procedures existing between the Depositary and the Warrant Agent, the number of
Warrants represented by the Global Warrant to be reduced by the number of
Warrants to be represented by the Definitive Warrant pursuant to Section 3.5(h)
hereof, and the Company shall execute and the Warrant Agent shall countersign
and deliver to the Person designated in the instructions a Definitive Warrant in
the appropriate amount. Any Definitive Warrant issued in exchange for a
beneficial interest in a Restricted Global Warrant pursuant to this Section
3.5(c) shall be registered in such name or names as the holder of such
beneficial interest shall instruct the Warrant Registrar through instructions
from the Depositary and the Participant or Indirect Participant. The Warrant
Agent shall deliver such Definitive Warrants to the Persons in whose names such
Warrants are so registered. Any Definitive Warrant issued in exchange for a
beneficial interest in a Restricted Global Warrant pursuant to this Section
3.5(c)(i) shall bear the Private Placement Legend and shall be subject to all
restrictions on transfer contained therein.

               (ii) Beneficial Interests in Restricted Global Warrants to
        Unrestricted Definitive Warrants. A holder of a beneficial interest in a
        Restricted Global Warrant may exchange such beneficial interest for an
        Unrestricted Definitive Warrant or may transfer such beneficial interest
        to a Person who takes delivery thereof in the form of an Unrestricted
        Definitive Warrant only if:

                    (A) such transfer is effected pursuant to the Registration
               Statement in accordance with the Warrant Registration Rights
               Agreement; or

                    (B) the Warrant Registrar receives the following:

                        (1) if the holder of such beneficial interest in a
                    Restricted Global Warrant proposes to exchange such
                    beneficial interest for a Definitive Warrant that does not
                    bear the Private Placement Legend, a certificate from such
                    holder in the form of Exhibit C hereto, including the
                    certifications in item (1)(b) thereof; or

                        (2) if the holder of such beneficial interest in a
                    Restricted Global Warrant proposes to transfer such
                    beneficial interest to a Person who shall take delivery
                    thereof in the form of a Definitive Warrant that does not
                    bear the Private Placement Legend, a certificate from such
                    holder in the form of Exhibit B hereto, including the
                    certifications in item (4) thereof;

               and, in each such case set forth in this subparagraph (B), if the
               Warrant Registrar so requests or if the Applicable Procedures so
               require, an Opinion of Counsel in form reasonably acceptable to
               the Warrant Registrar to the effect that such exchange or
               transfer is in compliance with the Securities Act and that the
               restrictions on transfer contained herein and in the Private
               Placement Legend are no longer required in order to maintain
               compliance with the Securities Act.

               (iii) Beneficial Interests in Unrestricted Global Warrants to
        Unrestricted Definitive Warrants. If any holder of a beneficial interest
        in an Unrestricted Global Warrant proposes to exchange such beneficial
        interest for a Definitive Warrant or to transfer such beneficial
        interest to a Person who takes delivery thereof in the form of a
        Definitive Warrant, then, upon satisfaction of the conditions set forth
        in Section 3.5(b)(ii) hereof, the Warrant Agent shall cause the amount
        of

                                       11

<PAGE>

        the applicable Global Warrant to be reduced accordingly pursuant to
        Section 3.5(h) hereof, and the Company shall execute and the Warrant
        Agent shall countersign and deliver to the Person designated in the
        instructions a Definitive Warrant in the appropriate principal amount.
        Any Definitive Warrant issued in exchange for a beneficial interest
        pursuant to this Section 3.5(c)(iii) shall be registered in such name or
        names and in such authorized denomination or denominations as the holder
        of such beneficial interest shall instruct the Warrant Registrar through
        instructions from the Depositary and the Participant or Indirect
        Participant. The Warrant Agent shall deliver such Definitive Warrants to
        the Persons in whose names such Warrants are so registered. Any
        Definitive Warrant issued in exchange for a beneficial interest pursuant
        to this Section 3.5(c)(iii) shall not bear the Private Placement Legend.

        (d)    Transfer and Exchange of Definitive Warrants for Beneficial
               Interests.

               (i)  Restricted Definitive Warrants to Beneficial Interests in
        Restricted Global Warrants. If any Holder of a Restricted Definitive
        Warrant proposes to exchange such Warrant for a beneficial interest in a
        Restricted Global Warrant or to transfer such Restricted Definitive
        Warrants to a Person who takes delivery thereof in the form of a
        beneficial interest in a Restricted Global Warrant, then, upon receipt
        by the Warrant Registrar of the following documentation:

                    (A) if the Holder of such Restricted Definitive Warrant
               proposes to exchange such Warrant for a beneficial interest in a
               Restricted Global Warrant, a certificate from such Holder in the
               form of Exhibit C hereto, including the certifications in item
               (2)(b) thereof;

                    (B) if such Restricted Definitive Warrant is being
               transferred to a QIB in accordance with Rule 144A under the
               Securities Act, a certificate to the effect set forth in Exhibit
               B hereto, including the certifications in item (1) thereof;

                    (C) if such Restricted Definitive Warrant is being
               transferred to a Non-U.S. Person in an offshore transaction in
               accordance with Rule 903 or Rule 904 under the Securities Act, a
               certificate to the effect set forth in Exhibit B hereto,
               including the certifications in item (2) thereof;

                    (D) if such Restricted Definitive Warrant is being
               transferred pursuant to an exemption from the registration
               requirements of the Securities Act in accordance with Rule 144
               under the Securities Act, a certificate to the effect set forth
               in Exhibit B hereto, including the certifications in item (3)(a)
               thereof

                    (E) if such Restricted Definitive Warrant is being
               transferred to an Institutional Accredited Investor in reliance
               on an exemption from the registration requirements of the
               Securities Act other than those listed in subparagraphs (B)
               through (D) above, a certificate to the effect set forth in
               Exhibit B hereto, including the certifications, certificates and
               Opinion of Counsel required by item (3) thereof, if applicable;

                    (F) if such Restricted Definitive Warrant is being
               transferred to the Company or any of its Subsidiaries, a
               certificate to the effect set forth in Exhibit B hereto,
               including the certifications in item (3)(b) thereof; or

                                       12

<PAGE>

                    (G) if such Restricted Definitive Warrant is being
               transferred pursuant to an effective registration statement under
               the Securities Act, a certificate to the effect set forth in
               Exhibit B hereto, including the certifications in item (3)(c)
               thereof,

        the Warrant Agent shall cancel the Restricted Definitive Warrant,
        increase or cause to be increased the amount of, in the case of clause
        (A) above, the appropriate Restricted Global Warrant, in the case of
        clause (B) above, the 144A Global Warrant, in the case of clause (C)
        above, the Regulation S Global Warrant, and in all other cases, the IAI
        Global Warrant.

               (ii) Restricted Definitive Warrants to Beneficial Interests in
        Unrestricted Global Warrants. A Holder of a Restricted Definitive
        Warrant may exchange such Warrant for a beneficial interest in an
        Unrestricted Global Warrant or transfer such Restricted Definitive
        Warrant to a Person who takes delivery thereof in the form of a
        beneficial interest in an Unrestricted Global Warrant only if:

                    (A) such transfer is effected pursuant to the Registration
               Statement in accordance with the Registration Rights Agreement;
               or

                    (B) the Warrant Registrar receives the following:

                        (1) if the Holder of such Definitive Warrants proposes
                    to exchange such Warrants for a beneficial interest in the
                    Unrestricted Global Warrant, a certificate from such Holder
                    in the form of Exhibit C hereto, including the
                    certifications in item (1)(c) thereof; or

                        (2) if the Holder of such Definitive Warrants proposes
                    to transfer such Warrants to a Person who shall take
                    delivery thereof in the form of a beneficial interest in the
                    Unrestricted Global Warrant, a certificate from such Holder
                    in the form of Exhibit B hereto, including the
                    certifications in item (4) thereof;

               and, in each such case set forth in this subparagraph (B), if the
               Warrant Registrar so requests or if the Applicable Procedures so
               require, an Opinion of Counsel in form reasonably acceptable to
               the Warrant Registrar to the effect that such exchange or
               transfer is in compliance with the Securities Act and that the
               restrictions on transfer contained herein and in the Private
               Placement Legend are no longer required in order to maintain
               compliance with the Securities Act.

               Upon satisfaction of the conditions of any of the subparagraphs
        in this Section 3.5(d)(ii), the Warrant Agent shall cancel the
        Definitive Warrants and increase or cause to be increased the aggregate
        principal amount of the Unrestricted Global Warrant.

               (iii) Unrestricted Definitive Warrants to Beneficial Interests in
        Unrestricted Global Warrants. A Holder of an Unrestricted Definitive
        Warrant may exchange such Warrant for a beneficial interest in an
        Unrestricted Global Warrant or transfer such Definitive Warrants to a
        Person who takes delivery thereof in the form of a beneficial interest
        in an Unrestricted Global Warrant at any time. Upon receipt of a request
        for such an exchange or transfer, the Warrant Agent shall cancel the
        applicable Unrestricted Definitive Warrant and increase or cause to be
        increased the amount of one of the Unrestricted Global Warrants.

                                       13

<PAGE>

               If any such exchange or transfer from a Definitive Warrant to a
        beneficial interest is effected pursuant to subparagraphs (ii)(B) or
        (iii) above at a time when an Unrestricted Global Warrant has not yet
        been issued, the Company shall issue and, upon receipt of an Warrant
        Countersignature Order in accordance with Section 3.2 hereof, the
        Warrant Agent shall countersign one or more Unrestricted Global Warrants
        in the number equal to the number of beneficial interests of Definitive
        Warrants so transferred.

        (e)    Transfer and Exchange of Definitive Warrants for Definitive
               Warrants.

               Upon request by a Holder of Definitive Warrants and such Holder's
compliance with the provisions of this Section 3.5(e), the Warrant Registrar
shall register the transfer or exchange of Definitive Warrants. Prior to such
registration of transfer or exchange, the requesting Holder shall present or
surrender to the Warrant Registrar the Definitive Warrants duly endorsed or
accompanied by a written instruction of transfer in form satisfactory to the
Warrant Registrar duly executed by such Holder or by its attorney, duly
authorized in writing. In addition, the requesting Holder shall provide any
additional certifications, documents and information, as applicable, required
pursuant to the following provisions of this Section 3.5(e).

               (i)  Restricted Definitive Warrants to Restricted Definitive
               Warrants. Any Restricted Definitive Warrant may be transferred to
               and registered in the name of Persons who take delivery thereof
               in the form of a Restricted Definitive Warrant if the Warrant
               Registrar receives the following:

                    (A) if the transfer will be made pursuant to Rule 144A under
               the Securities Act, then the transferor must deliver a
               certificate in the form of Exhibit B hereto, including the
               certifications in item (1) thereof;

                    (B) if the transfer will be made pursuant to Rule 903 or
               Rule 904, then the transferor must deliver a certificate in the
               form of Exhibit B hereto, including the certifications in item
               (2) thereof; or

                    (C) if the transfer will be made pursuant to any other
               exemption from the registration requirements of the Securities
               Act, then the transferor must deliver a certificate in the form
               of Exhibit B hereto, including the certifications, certificates
               and Opinion of Counsel required by item (3) thereof, if
               applicable.

               (ii) Restricted Definitive Warrants to Unrestricted Definitive
          Warrants. Any Restricted Definitive Warrant may be exchanged by the
          Holder thereof for an Unrestricted Definitive Warrant or transferred
          to a Person or Persons who take delivery thereof in the form of an
          Unrestricted Definitive Warrant if:

                    (A) any such transfer is effected pursuant to the
               Registration Statement in accordance with the Warrant
               Registration Rights Agreement; or

                    (B) the Warrant Registrar receives the following:

                        (1) if the Holder of such Restricted Definitive
                    Warrants proposes to exchange such Warrants for an
                    Unrestricted Definitive Warrant, a certificate from such
                    Holder in the form of Exhibit C hereto, including the
                    certifications in item (1)(d) thereof; or

                                       14

<PAGE>

                        (2) if the Holder of such Restricted Definitive
                    Warrants proposes to transfer such Warrants to a Person who
                    shall take delivery thereof in the form of an Unrestricted
                    Definitive Warrant, a certificate from such Holder in the
                    form of Exhibit B hereto, including the certifications in
                    item (4) thereof;

               and, in each such case set forth in this subparagraph (B), if the
               Warrant Registrar so requests, an Opinion of Counsel in form
               reasonably acceptable to the Company to the effect that such
               exchange or transfer is in compliance with the Securities Act and
               that the restrictions on transfer contained herein and in the
               Private Placement Legend are no longer required in order to
               maintain compliance with the Securities Act.

               (iii) Unrestricted Definitive Warrants to Unrestricted Definitive
        Warrants. A Holder of Unrestricted Definitive Warrants may transfer such
        Warrants to a Person who takes delivery thereof in the form of an
        Unrestricted Definitive Warrant. Upon receipt of a request to register
        such a transfer, the Warrant Registrar shall register the Unrestricted
        Definitive Warrants pursuant to the instructions from the Holder
        thereof.

        (f)    Registration Statement.

               Upon the effectiveness of the Registration Statement and sales of
Warrants in connection therewith in accordance with the Warrant Registration
Rights Agreement, the Company shall issue and, upon receipt of a Warrant
Countersignature Order in accordance with Section 3.2, the Warrant Agent shall
countersign (i) one or more Unrestricted Global Warrants in an amount equal to
the amount of the beneficial interests in the Restricted Global Warrants sold
under such Registration Statement and (ii) Unrestricted Definitive Warrants in
an amount equal to the amount of the beneficial interests of the Restricted
Definitive Warrants sold under such Registration Statement. Concurrently with
the issuance of such Warrants, the Warrant Agent shall cause the amount of the
applicable Restricted Global Warrants to be reduced accordingly, and the Company
shall execute and the Warrant Agent shall countersign and deliver to the Persons
designated by the Holders of Definitive Warrants so accepted Unrestricted
Definitive Warrants in the appropriate amount.

        (g)    Legends.

               The following legends shall appear on the face of all Global
Warrants and Definitive Warrants issued under this Warrant Agreement unless
specifically stated otherwise in the applicable provisions of this Warrant
Agreement.

               (i)  Private Placement Legend.

                    (C) Except as permitted by subparagraph (B) below, each
               Global Warrant and each Definitive Warrant (and all Warrants
               issued in exchange therefor or substitution thereof) shall bear
               the legend in substantially the following form unless otherwise
               agreed by the Company and the holder thereof:

               "THIS SECURITY (OR ITS PREDECESSOR) AND THE WARRANT SHARES TO BE
        ISSUED UPON ITS EXERCISE WAS ORIGINALLY ISSUED IN A TRANSACTION EXEMPT
        FROM REGISTRATION UNDER THE UNITED STATES SECURITIES ACT OF 1933 (THE
        "SECURITIES ACT"). ACCORDINGLY, THIS SECURITY MAY NOT BE OFFERED, SOLD
        OR OTHERWISE TRANSFERRED IN THE ABSENCE OF SUCH REGISTRATION OR AN
        APPLICABLE EXEMPTION THEREFROM. EACH PURCHASER

                                       15

<PAGE>

        OF THIS SECURITY IS HEREBY NOTIFIED THAT THE SELLER OF THIS SECURITY MAY
        BE RELYING ON THE EXEMPTION FROM THE PROVISIONS OF SECTION 5 OF THE
        SECURITIES ACT PROVIDED BY RULE 144A THEREUNDER.

               THE HOLDER OF THIS SECURITY AGREES FOR THE BENEFIT OF THE COMPANY
        THAT (A) THIS SECURITY MAY BE OFFERED, RESOLD, PLEDGED OR OTHERWISE
        TRANSFERRED, ONLY (I) IN THE UNITED STATES TO A PERSONWHOM THE SELLER
        REASONABLY BELIEVES IS A QUALIFIED INSTITUTIONAL BUYER (AS DEFINED IN
        RULE 144A UNDER THE SECURITIES ACT) IN A TRANSACTION MEETING THE
        REQUIREMENTS OF RULE 144A, (II) OUTSIDE THE UNITED STATES IN AN OFFSHORE
        TRANSACTION IN ACCORDANCE WITH RULE 904 UNDER THE SECURITIES ACT, (III)
        PURSUANT TO AN EXEMPTION FROM REGISTRATION UNDER THE SECURITIES ACT
        PROVIDED BY RULE 144 THEREUNDER (IF AVAILABLE) OR (IV) PURSUANT TO AN
        EFFECTIVE REGISTRATION STATEMENT UNDER THE SECURITIES ACT, IN EACH OF
        CASES (I) THROUGH (IV) IN ACCORDANCE WITH ANY APPLICABLE SECURITIES LAWS
        OF ANY STATE OF THE UNITED STATES, AND (B) THE HOLDERWILL, AND EACH
        SUBSEQUENT HOLDER IS REQUIRED TO, NOTIFY ANY PURCHASER OF THIS NOTE FROM
        IT OF THE RESALE RESTRICTIONS REFERRED TO IN (A) ABOVE.

               THE HOLDER OF THIS SECURITY AGREES NOT TO ENGAGE IN HEDGING
        TRANSACTIONS UNLESS IN COMPLIANCE WITH THE SECURITIES ACT AND (4) AGREES
        THAT IT WILL DELIVER TO EACH PERSON TO WHOM THIS SECURITY OR AN INTEREST
        HEREIN IS TRANSFERRED A NOTICE SUBSTANTIALLY TO THE EFFECT OF THIS
        LEGEND.

               AS USED HEREIN, THE TERMS "OFFSHORE TRANSACTION" AND "UNITED
        STATES" HAVE THE MEANINGS GIVEN TO THEM BY RULE 902 OF REGULATION S
        UNDER THE SECURITIES ACT. THE WARRANT AGREEMENT CONTAINS A PROVISION
        REQUIRING THE WARRANT AGENT TO REFUSE TO REGISTER ANY TRANSFER OF THIS
        SECURITY IN VIOLATION OF THE FOREGOING."

                    (B) Notwithstanding the foregoing, any Global Warrant or
               Definitive Warrant issued pursuant to subparagraphs (b)(iv),
               (c)(ii), (c)(iii), (d)(ii), (d)(iii), (e)(ii), (e)(iii) or (f) to
               this Section 3.5 (and all Warrants issued in exchange therefor or
               substitution thereof) shall not bear the Private Placement
               Legend.

               (ii) Global Warrant Legend. Each Global Warrant shall bear a
        legend in substantially the following form unless otherwise agreed by
        the Company and the holder thereof:

               "THIS GLOBAL WARRANT IS HELD BY THE DEPOSITARY (AS DEFINED IN THE
        WARRANT AGREEMENT GOVERNING THIS WARRANT) OR ITS NOMINEE IN CUSTODY FOR
        THE BENEFIT OF THE BENEFICIAL OWNERS HEREOF, AND IS NOT TRANSFERABLE TO
        ANY PERSON UNDER ANY CIRCUMSTANCES EXCEPT THAT (I) THE WARRANT AGENT MAY
        MAKE SUCH NOTATIONS HEREON AS MAY BE REQUIRED PURSUANT TO SECTION 3.5 OF
        THE WARRANT AGREEMENT, (II) THIS GLOBAL WARRANT MAY BE EXCHANGED IN
        WHOLE BUT NOT IN PART PURSUANT TO SECTION 3.5(A) OF THE WARRANT
        AGREEMENT, (III) THIS GLOBAL WARRANT MAY BE DELIVERED TO THE WARRANT
        AGENT FOR CANCELLATION

                                       16

<PAGE>

        PURSUANT TO SECTION 3.8 OF THE WARRANT AGREEMENT AND (IV) THIS GLOBAL
        WARRANT MAY BE TRANSFERRED TO A SUCCESSOR DEPOSITARY WITH THE PRIOR
        WRITTEN CONSENT OF AMERICAN TOWER CORPORATION (THE "COMPANY")."

               (iii) Unit Legend. Each Warrant issued prior to the Separation
        Date will bear a legend to the following effect unless otherwise agreed
        by the Company and the holder thereof:

               "THE WARRANTS EVIDENCED BY THIS CERTIFICATE ARE INITIALLY ISSUED
        AS PART OF AN ISSUANCE OF UNITS (THE "UNITS"), EACH OF WHICH CONSISTS OF
        $1,000 PRINCIPAL AMOUNT AT MATURITY OF THE 12.25% SENIOR SUBORDINATED
        DISCOUNT NOTES DUE 2008 (THE "NOTES") OF ESCROW CORP. AND ONE WARRANT TO
        PURCHASE 14.0953 SHARES, PAR VALUE $0.01 PER SHARE, OF AMERICAN TOWER
        CORPORATION.

               PRIOR TO THE EARLIEST TO OCCUR OF (I) 180 DAYS AFTER THE CLOSING
        OF THE OFFERING, (II) THE DATE ON WHICH A REGISTRATION STATEMENT FOR A
        REGISTERED EXCHANGE OFFER WITH RESPECT TO THE NOTES IS DECLARED
        EFFECTIVE UNDER THE SECURITIES ACT, (III) THE DATE A SHELF REGISTRATION
        STATEMENT WITH RESPECT TO THE WARRANTS IS DECLARED EFFECTIVE UNDER THE
        SECURITIES ACT, (IV) SUCH DATE AS CREDIT SUISSE FIRST BOSTON LLC IN ITS
        SOLE DISCRETION SHALL DETERMINE AND (V) IN THE EVENT OF A CHANGE OF
        CONTROL, THE DATE AMERICAN TOWER ESCROW CORPORATION (OR ITS SUCCESSOR)
        MAILS THE REQUISITE NOTICE TO THE HOLDERS, THE WARRANTS EVIDENCED BY
        THIS CERTIFICATE MAY NOT BE TRANSFERRED OR EXCHANGED SEPARATELY FROM,
        BUT MAY BE TRANSFERRED OR EXCHANGED ONLY TOGETHER WITH, THE NOTES."

               (iv) Regulation S Legend. Each Warrant that is a Registrable
        Security and issued pursuant to Regulation S shall bear the following
        legend in substantially the following form unless otherwise agreed by
        the Company and the holder thereof:

               "THIS WARRANT AND THE SECURITIES TO BE ISSUED UPON ITS EXERCISE
        HAVE NOT BEEN REGISTERED UNDER THE SECURITIES ACT AND THE WARRANT MAY
        NOT BE EXERCISED BY OR ON BEHALF OF ANY U.S. PERSON UNLESS REGISTERED
        UNDER THE U.S. SECURITIES ACT OF 1933, AS AMENDED (THE "SECURITIES ACT")
        OR AN EXEMPTION FROM SUCH REGISTRATION IS AVAILABLE. IN ORDER TO
        EXERCISE THIS WARRANT, THE HOLDER MUST FURNISH TO THE COMPANY AND THE
        WARRANT AGENT EITHER (A) A WRITTEN CERTIFICATION THAT IT IS NOT A U.S.
        PERSON AND THE WARRANT IS NOT BEING EXERCISED ON BEHALF OF A U.S. PERSON
        OR (B) A WRITTEN OPINION OF COUNSEL TO THE EFFECT THAT THE SECURITIES
        DELIVERED UPON EXERCISE OF THE WARRANT HAVE BEEN REGISTERED UNDER THE
        SECURITIES ACT OR THAT THE DELIVERY OF SUCH SECURITIES IS EXEMPT FROM
        THE REGISTRATION REQUIREMENTS OF THE SECURITIES ACT. TERMS IN THIS
        LEGEND HAVE THE MEANINGS GIVEN TO THEM BY REGULATION S UNDER THE
        SECURITIES ACT."

        (h)    Cancellation and/or Adjustment of Global Warrants.

                                       17

<PAGE>

               At such time as all beneficial interests in a particular Global
Warrant have been exercised or exchanged for Definitive Warrants or a particular
Global Warrant has been exercised, redeemed, repurchased or canceled in whole
and not in part, each such Global Warrant shall be returned to or retained and
canceled by the Warrant Agent in accordance with Section 3.8 hereof. At any time
prior to such cancellation, if any beneficial interest in a Global Warrant is
exercised or exchanged for or transferred to a Person who will take delivery
thereof in the form of a beneficial interest in another Global Warrant or for
Definitive Warrants, the amount of Warrants represented by such Global Warrant
shall be reduced accordingly and an endorsement shall be made on such Global
Warrant by the Warrant Agent or by the Depositary at the direction of the
Warrant Agent to reflect such reduction; and if the beneficial interest is being
exchanged for or transferred to a Person who will take delivery thereof in the
form of a beneficial interest in another Global Warrant, such other Global
Warrant shall be increased accordingly and an endorsement shall be made on such
Global Warrant by the Warrant Agent or by the Depositary at the direction of the
Warrant Agent to reflect such increase.

        (i)    General Provisions Relating to Transfers and Exchanges.

               (i) To permit registrations of transfers and exchanges, the
        Company shall execute and the Warrant Agent shall countersign Global
        Warrants and Definitive Warrants upon the Company's order or at the
        Warrant Registrar's request.

               (ii) No service charge shall be made to a holder of a beneficial
        interest in a Global Warrant or to a holder of a Definitive Warrant for
        any registration of transfer or exchange, but the Company may require
        payment of a sum sufficient to cover any transfer tax or similar
        governmental charge payable in connection therewith.

               (iii) All Global Warrants and Definitive Warrants issued upon any
        registration of transfer or exchange of Global Warrants or Definitive
        Warrants shall be the duly authorized, executed and issued warrants for
        Common Stock of the Company, not subject to any preemptive rights, and
        entitled to the same benefits under this Warrant Agreement, as the
        Global Warrants or Definitive Warrants surrendered upon such
        registration of transfer or exchange.

               (iv) Prior to due presentment for the registration of a transfer
        of any Warrant, the Warrant Agent, and the Company may deem and treat
        the Person in whose name any Warrant is registered as the absolute owner
        of such Warrant for all purposes and none of the Warrant Agent, or the
        Company shall be affected by notice to the contrary.

               (v) The Warrant Agent shall countersign Global Warrants and
        Definitive Warrants in accordance with the provisions of Section 3.2
        hereof.

        (j)    Facsimile Submissions to Warrant Agent.

               All certifications, certificates and Opinions of Counsel required
to be submitted to the Warrant Registrar pursuant to this Section 3.5 to effect
a registration of transfer or exchange may be submitted by facsimile.

               Notwithstanding anything herein to the contrary, as to any
certificates and/or certifications delivered to the Warrant Registrar pursuant
to this Section 3.5, the Warrant Registrar's duties shall be limited to
confirming that any such certifications and certificates delivered to it are in
the form of Exhibits B and C attached hereto. The Warrant Registrar shall not be
responsible for confirming the truth or accuracy of representations made in any
such certifications or certificates. As to any Opinions

                                       18

<PAGE>

of Counsel delivered pursuant to this Section 3.5, the Warrant Registrar may
rely upon, and be fully protected in relying upon, such opinions.

        3.6.   REPLACEMENT WARRANTS.

               If any mutilated Warrant is surrendered to the Warrant Agent or
the Company and the Warrant Agent receives evidence to its satisfaction of the
destruction, loss or theft of any Warrant, the Company shall issue and the
Warrant Agent, upon receipt of a Warrant Countersignature Order, shall
countersign a replacement Warrant if the Warrant Agent's requirements are met.
If required by the Warrant Agent or the Company, an indemnity bond must be
supplied by the Holder that is sufficient in the judgment of the Warrant Agent
and the Company to protect the Company, the Warrant Agent, any Agent and any
agent for purposes of the countersignature from any loss that any of them may
suffer if a Warrant is replaced. The Company may charge for its expenses in
replacing a Warrant.

               Every replacement Warrant is an additional warrant of the Company
and shall be entitled to all of the benefits of this Warrant Agreement equally
and proportionately with all other Warrants duly issued hereunder.

        3.7.   TEMPORARY WARRANTS.

               Until certificates representing Warrants are ready for delivery,
the Company may prepare and the Warrant Agent, upon receipt of a Warrant
Countersignature Order, shall issue temporary Warrants. Temporary Warrants shall
be substantially in the form of certificated Warrants but may have variations
that the Company considers appropriate for temporary Warrants and as shall be
reasonably acceptable to the Warrant Agent. Without unreasonable delay, the
Company shall prepare and the Warrant Agent, as soon as practicable upon receipt
of the written order of the Company signed by an officer of the Company, shall
countersign definitive Warrants in exchange for temporary Warrants.

               Holders of temporary Warrants shall be entitled to all of the
benefits of this Warrant Agreement.

        3.8.   CANCELLATION.

               Subject to Section 3.5(h) hereof, the Company at any time may
deliver Warrants to the Warrant Agent for cancellation. The Warrant Registrar
and Warrant Paying Agent shall forward to the Warrant Agent any Warrants
surrendered to them for registration of transfer, exchange or exercise. The
Warrant Agent and no one else shall cancel all Warrants surrendered for
registration of transfer, exchange, exercise, replacement or cancellation and
shall dispose of such canceled Warrants in its customary manner. The Company may
not issue new Warrants to replace Warrants that have been exercised or that have
been delivered to the Warrant Agent for cancellation.

SECTION 4.          SEPARATION OF WARRANTS; TERMS OF WARRANTS; EXERCISE OF
                    WARRANTS

               (a)  The Notes and Warrants will not be separately transferable
until the Separation Date. Subject to the terms of this Agreement, each Warrant
holder shall have the right, which may be exercised during the period commencing
at the opening of business on January 29, 2006 until August 1, 2008 (the
"Exercise Period"), to receive from the Company the number of fully paid and
nonassessable Warrant Shares which the holder may at the time be entitled to
receive on exercise of such Warrants and payment of the Exercise Price (i) by
tendering Notes having an Accreted Value to the date of exercise

                                       19

<PAGE>

equal to the Exercise Price (ii) by tendering Warrants as set forth below, (iii)
by tendering any combination of Notes and Warrants or (iv) in cash in United
States dollars by wire transfer or by certified or official bank check payable
to the order of the Company the Exercise Price then in effect for such Warrant
Shares; provided that holders shall be able to exercise their Warrants only if a
registration statement relating to the Warrant Shares is then in effect, or the
exercise of such Warrants is exempt from the registration requirements of the
Securities Act, and such securities are qualified for sale or exempt from
qualification under the applicable securities laws of the states in which the
various holders of the Warrants or other persons to whom it is proposed that the
Warrant Shares be issued on exercise of the Warrants reside. Each holder may
exercise its right during the Exercise Period, to receive Warrant Shares on a
net basis, such that, without the exchange of any funds, the holder will receive
such number of Warrant Shares equal to the product of (A) the number of Warrant
Shares for which such Warrant is exercisable as of the date of exercise (if the
Exercise Price were being paid in cash) and (B) the Cashless Exercise Ratio. The
Cashless Exercise Ratio shall equal a fraction the numerator of which is the
Market Value per share of Common Stock minus the Exercise Price per share as of
the date of exercise and the denominator of which is the Market Value per share
on the date of exercise. Each Warrant not exercised on or prior to August 1,
2008 (the "Expiration Date") shall become void and all rights thereunder and all
rights in respect thereof under this agreement shall cease as of such time. No
adjustments as to dividends will be made upon exercise of the Warrants.
Notwithstanding the foregoing, if the Escrow Corp. Merger has not been
consummated and the Notes have been mandatorily redeemed pursuant to Section
3.08 of the Indenture (the "Redemption Date"), each Warrant shall become void
and all rights thereunder and all rights in respect thereof under this Agreement
shall cease as of the Redemption Date.

               (b)  In order to exercise all or any of the Warrants represented
by a Warrant Certificate, the holder thereof must deliver to the Warrant Agent
at its corporate trust office set forth in Section 15 hereof the Warrant
Certificate and the form of election to purchase on the reverse thereof duly
filled in and signed, which signature shall be medallion guaranteed by an
institution which is a member of a Securities Transfer Association recognized
signature guarantee program, and upon payment to the Warrant Agent for the
account of the Company of the Exercise Price, which is set forth in the form of
Warrant Certificate attached hereto as Exhibit A, as adjusted as herein
provided, for the number of Warrant Shares in respect of which such Warrants are
then exercised. Payment of the aggregate Exercise Price shall be made in the
manner provided in Section 4(a) hereof.

               (c)  Subject to the provisions of Section 5 hereof, upon
compliance with clause (b) above, the Warrant Agent shall deliver or cause to be
delivered with all reasonable dispatch, to or upon the written order of the
holder and in such name or names as the Warrant holder may designate, a
certificate or certificates for the number of whole Warrant Shares issuable upon
the exercise of such Warrants or other securities or property to which such
holder is entitled hereunder, together with cash as provided in Section 9
hereof; provided that if any consolidation, merger or lease or sale of assets is
proposed to be effected by the Company as described in Section 8(k) hereof, or a
tender offer or an exchange offer for shares of Common Stock shall be made, upon
such surrender of Warrants and payment of the Exercise Price as aforesaid, the
Warrant Agent shall, as soon as reasonably possible, deliver or cause to be
delivered the full number of Warrant Shares issuable upon the exercise of such
Warrants in the manner described in this sentence or other securities or
property to which such holder is entitled hereunder, together with cash as
provided in Section 9 hereof. Such certificate or certificates shall be deemed
to have been issued and any person so designated to be named therein shall be
deemed to have become a holder of record of such Warrant Shares as of the date
of the surrender of such Warrants and payment of the Exercise Price.

               (d)  The Warrants shall be exercisable, at the election of the
holders thereof, either in full or from time to time in part pursuant to the
terms of this Section 4. If less than all the Warrants

                                       20

<PAGE>

represented by a Warrant Certificate are exercised, such Warrant Certificate
shall be surrendered and a new Warrant Certificate of the same tenor and for the
number of Warrants which were not exercised shall be executed by the Company and
delivered to the Warrant Agent and the Warrant Agent shall countersign the new
Warrant Certificate, registered in such name or names as may be directed in
writing by the holder, and shall deliver the new Warrant Certificate to the
Person or Persons entitled to receive the same.

               (e)  All Warrant Certificates surrendered upon exercise of
Warrants shall be cancelled by the Warrant Agent. Such cancelled Warrant
Certificates shall then be disposed of by the Warrant Agent in its customary
manner. The Warrant Agent shall account promptly to the Company with respect to
Warrants exercised and concurrently pay to the Company all monies received by
the Warrant Agent for the purchase of the Warrant Shares through the exercise of
such Warrants.

               (f)  The Warrant Agent shall keep copies of this Agreement and
any notices given or received hereunder available for inspection by the holders
upon reasonable prior written notice during normal business hours at its office.
The Company shall supply the Warrant Agent from time to time with such numbers
of copies of this Agreement as the Warrant Agent may request.

               (g)  The Company has agreed pursuant to the Warrant Registration
Rights Agreement to file within 90 days after the issuance of the Warrants and
use its reasonable best efforts to make effective, subject to certain exceptions
detailed in the Warrant Registration Rights Agreement, on or before 180 days
after such date a shelf registration statement covering the resale of the
Warrants, the issuance by the Company's common stock upon the exercise of the
warrants resold pursuant to such registration statement and the resale of the
Warrant Shares by the holder thereof on the appropriate form under the
Securities Act, and to use its reasonable best efforts (subject to certain
"black-out" periods not to exceed 60 days in any calendar year subject to
extension for 30 days in certain circumstances) to keep such registration
statement continuously effective under the Securities Act, subject to certain
exceptions, until two years following the Closing Date.

               (h)  The holders of the warrants will have no right to vote on
matters submitted to the stockholders of the Company and will have no right to
receive dividends. The holders of the warrants will not be entitled to share in
the assets of the Company in the event of liquidation, dissolution or the
winding up of the Company. In the event a bankruptcy or reorganization is
commenced by or against the Company, a bankruptcy court may hold that
unexercised warrants are executory contracts which may be subject to rejection
by the Company with approval of the bankruptcy court, and the holders of the
warrants may, even if sufficient funds are available, receive nothing or a
lesser amount as a result of any such bankruptcy case than they would be
entitled to if they had exercised their warrants prior to the commencement of
any such case.

SECTION 5.          PAYMENT OF TAXES.

               The Company will pay all documentary stamp taxes attributable to
the initial issuance of Warrant Shares upon the exercise of Warrants; provided
that the Company shall not be required to pay any tax or taxes which may be
payable in respect of any transfer involved in the issue of any Warrant
Certificates or any certificates for Warrant Shares in a name other than that of
the registered holder of a Warrant Certificate surrendered upon the exercise of
a Warrant, and the Company shall not be required to issue or deliver such
Warrant Certificates unless or until the person or persons requesting the
issuance thereof shall have paid to the Company the amount of such tax or shall
have established to the satisfaction of the Company that such tax has been paid;
provided further that the Company shall not be required to pay any tax or taxes
which may be payable in the event of a taxable distribution to holders of the
Company's common stock that results in an adjustment to the number of Warrant
Shares or other

                                       21

<PAGE>

consideration for which a Warrant may be exercised, and results in the holders
of the Warrants to be deemed to have received a distribution subject to United
States federal income tax as a dividend.

SECTION 6.          RESERVATION OF WARRANT SHARES.

               (a)  The Company will at all times reserve and keep available,
free from preemptive rights, out of the aggregate of its authorized but unissued
Common Stock or its authorized and issued Common Stock held in its treasury, for
the purpose of enabling it to satisfy any obligation to issue Warrant Shares
upon exercise of Warrants, the maximum number of shares of Common Stock which
may then be deliverable upon the exercise of all outstanding Warrants.

               (b)  The Company or, if appointed, the transfer agent for the
Common Stock (the "Transfer Agent") and every subsequent transfer agent for any
shares of the Company's capital stock issuable upon the exercise of any of the
rights of purchase aforesaid will be irrevocably authorized and directed at all
times to reserve such number of authorized shares as shall be required for such
purpose. The Company will keep a copy of this Agreement on file with the
Transfer Agent and with every subsequent transfer agent for any shares of the
Company's capital stock issuable upon the exercise of the rights of purchase
represented by the Warrants. The Warrant Agent is hereby irrevocably authorized
to requisition from time to time from such Transfer Agent the stock certificates
required to honor outstanding Warrants upon exercise thereof in accordance with
the terms of this Agreement. The Company will supply such Transfer Agent with
duly executed certificates for such purposes and will provide or otherwise make
available any cash which may be payable as provided in Section 9 hereof. The
Company will furnish such Transfer Agent a copy of all notices of adjustments,
and certificates related thereto, transmitted to each holder pursuant to Section
11 hereof.

               (c)  The Company covenants that all Warrant Shares which may be
issued upon exercise of Warrants will, upon issue, be fully paid, nonassessable,
free of preemptive rights and free from all taxes, liens, charges and security
interests with respect to the issuance thereof.

SECTION 7.          OBTAINING STOCK EXCHANGE LISTINGS.

               The Company will from time to time take all action which may be
necessary so that the Warrant Shares, immediately upon their issuance upon the
exercise of Warrants, will be listed on the principal securities exchanges,
automated quotation systems or other markets within the United States of
America, if any, on which other shares of Common Stock are then listed, if any.

SECTION 8.          ADJUSTMENT OF EXERCISE PRICE AND NUMBER OF WARRANT SHARES
                    ISSUABLE.

               The Exercise Price and the number of Warrant Shares issuable upon
the exercise of each Warrant are subject to adjustment from time to time upon
the occurrence of the events enumerated in this Section 8. For purposes of this
Section 8, "Common Stock" means shares now or hereafter authorized of any class
of common stock of the Company and any other stock of the Company, however
designated, that has the right (subject to any prior rights of any class or
series of preferred stock) to participate in any distribution of the assets or
earnings of the Company without limit as to per share amount.

               (a)  Adjustment for Change in Capital Stock.

                                       22

<PAGE>

               If the Company (i) pays a dividend or makes a distribution on its
Common Stock in shares of its Common Stock, (ii) subdivides its outstanding
shares of Common Stock into a greater number of shares, (iii) combines its
outstanding shares of Common Stock into a smaller number of shares, (iv) makes a
distribution on its Common Stock in shares of its capital stock other than
Common Stock or (v) issues by reclassification of its Common Stock any shares of
its capital stock, then the Exercise Price in effect immediately prior to such
action shall be proportionately adjusted so that the holder of any Warrant
thereafter exercised may receive the aggregate number and kind of shares of
capital stock of the Company which he would have owned immediately following
such action if such Warrant had been exercised immediately prior to such action.

               The adjustment shall become effective immediately after the
record date in the case of a dividend or distribution and immediately after the
effective date in the case of a subdivision, combination or reclassification.
If, after an adjustment, a holder of a Warrant upon exercise of it may receive
shares of two or more classes of capital stock of the Company, the Company shall
determine, in good faith, the allocation of the adjusted Exercise Price between
the classes of capital stock. After such allocation, the exercise privilege and
the Exercise Price of each class of capital stock shall thereafter be subject to
adjustment on terms comparable to those applicable to Common Stock in this
Section 8. Such adjustment shall be made successively whenever any event listed
above shall occur.

               (b)  Adjustment for Rights Issue.

               If the Company distributes any rights, options or warrants to all
holders of its Common Stock entitling them for a period expiring within 45 days
after the record date mentioned below to purchase shares of Common Stock at a
price per share less than the Fair Value per share on that record date, the
Exercise Price shall be adjusted in accordance with the formula:

                        O + N X P
                            -----
            E' = E X          M
                     ---------------
                         O + N
where:

                E'       =        the adjusted Exercise Price.

                E        =        the current Exercise Price.

                O        =        the number of shares of Common Stock
                                  outstanding on the record date.

                N        =        the number of additional shares of Common
                                  Stock issued pursuant to such rights,
                                  options or warrants.

                P        =        the aggregate price per share of the
                                  additional shares.

                M        =        the Fair Value per share of Common Stock on
                                  the record date.

               The adjustment shall be made successively whenever any such
rights, options or warrants are issued and shall become effective immediately
after the record date for the determination of stockholders entitled to receive
the rights, options or warrants. If at the end of the period during which such
rights, options or warrants are exercisable, not all rights, options or warrants
shall have been

                                       23

<PAGE>

exercised, the Exercise Price shall be immediately readjusted to what it would
have been if "N" in the above formula had been the number of shares actually
issued.

               (c)  Adjustment for Other Distributions.

               If the Company distributes to all holders of its Common Stock any
of its assets or debt securities or any rights or warrants to purchase debt
securities of the Company, the Exercise Price shall be adjusted in accordance
with the formula:

                         M  -  F
           E' =  E  X   ---------
                            M
where:

             E'       =        the adjusted Exercise Price.

             E        =        the current Exercise Price.

             M        =        the Fair Value per share of Common Stock on the
                               record date mentioned below.

             F        =        the fair market value on the record date
                               of the assets, securities, rights or
                               warrants to be distributed in respect of one
                               share of Common Stock as determined in good
                               faith by the Board of Directors of the
                               Company (the "Board of Directors").

               The adjustment shall be made successively whenever any such
distribution is made and shall become effective immediately after the record
date for the determination of stockholders entitled to receive the distribution.

               This Section 8(c) does not apply to cash dividends or cash
distributions paid out of consolidated current or retained earnings as shown on
the books of the Company prepared in accordance with generally accepted
accounting principles. Also, this Section 8(c) does not apply to rights, options
or warrants referred to in Section 8(b) hereof.

               (d)  Adjustment for Common Stock Issue.

               If the Company issues shares of Common Stock for a consideration
per share less than the Fair Value per share on the date the Company fixes the
offering price of such additional shares, the Exercise Price shall be adjusted
in accordance with the formula:

                            P
                           ---
           E' = E  X  O  +  M
                    -----------
                      A
where:

              E'       =        the adjusted Exercise Price.

                                       24

<PAGE>

              E        =        the then current Exercise Price.

              O        =        the number of shares outstanding immediately
                                prior to the issuance of such additional
                                shares.

              P        =        the aggregate consideration received for the
                                issuance of such additional
                                shares.

              M        =        the Fair Value per share on the date of issuance
                                of such additional shares.

              A        =        the number of shares outstanding
                                immediately after the issuance of such
                                additional shares.

               The adjustment shall be made successively whenever any such
issuance is made, and shall become effective immediately after such issuance.

               This subsection (d) does not apply to:

                    (1) any of the transactions described in subsections (a),
        (b), (c) and (e) of this Section 8,

                    (2) the exercise of Warrants, or the conversion or exchange
        of other securities convertible or exchangeable for Common Stock the
        issuance of which caused an adjustment to be made under Section 8(e),

                    (3) Common Stock issued to the Company's employees (or
        employees of its subsidiaries) under bona fide employee benefit plans
        adopted by the Board of Directors and approved by the holders of Common
        Stock when required by law, if such Common Stock would otherwise be
        covered by this subsection (d) (but only to the extent that the
        aggregate number of shares excluded hereby and issued after the date of
        this Warrant Agreement shall not exceed 10% of the Common Stock
        outstanding at the time of the adoption of each such plan, exclusive of
        anti-dilution adjustments thereunder),

                    (4) Common Stock issued to shareholders of any person which
        merges into the Company, or with a subsidiary of the Company, in
        proportion to their stock holdings of such person immediately prior to
        such merger, upon such merger, provided that if such person is an
        Affiliate of the Company, the Board of Directors shall have obtained a
        fairness opinion from a nationally recognized investment banking,
        appraisal or valuation firm, which is not an Affiliate of the Company,
        stating that the consideration received in such merger is fair to the
        Company from a financial point of view, or

                    (5) the issuance of shares of Common Stock pursuant to
        rights, options, warrants or convertible securities which were
        originally issued in a Non-Affiliate Sale (as defined below) together
        with one or more other securities as part of a unit at a price per unit.

               (e)  Adjustment for Convertible Securities Issue.

               If the Company issues any securities convertible into or
exchangeable for Common Stock (other than securities issued in transactions
described in subsections (b) and (c) of this Section 8) for a consideration per
share of Common Stock initially deliverable upon conversion or exchange of such

                                       25

<PAGE>

securities less than the Fair Value per share on the date of issuance of such
securities, the Exercise Price shall be adjusted in accordance with this
formula:

                                 P
                                ---
                             O + M
            E'   =    E X  ----------
                             O + D
where:

                 E'     =    the adjusted Exercise Price.

                 E      =    the then current Exercise Price.

                 O      =    the number of shares  outstanding  immediately
                             prior to the  issuance  of such securities.

                 P      =    the aggregate consideration received for the
                             issuance of such securities.

                 M      =    the Fair Value per share on the date of issuance
                             of such securities.

                 D      =    the maximum number of shares deliverable upon
                             conversion or in exchange for such securities at
                             the initial conversion or exchange rate.

               The adjustment shall be made successively whenever any such
               issuance is made, and shall become effective immediately after
               such issuance.

               If all of the Common Stock deliverable upon conversion or
exchange of such securities have not been issued when such securities are no
longer outstanding, then the Exercise Price shall promptly be readjusted to the
Exercise Price which would then be in effect had the adjustment upon the
issuance of such securities been made on the basis of the actual number of
shares of Common Stock issued upon conversion or exchange of such securities.

               This subsection (e) does not apply to convertible securities
issued to shareholders of any person which merges into the Company, or with a
subsidiary of the Company, in proportion to their stock holdings of such person
immediately prior to such merger, upon such merger, provided that if such person
is an Affiliate of the Company, the Board of Directors shall have obtained a
fairness opinion from a nationally recognized investment banking, appraisal or
valuation firm, which is not an Affiliate of the Company, stating that the
consideration received in such merger is fair to the Company from a financial
point of view.

               (f)  Consideration Received.

               For purposes of any computation respecting consideration received
pursuant to subsections (d), and (e) of this Section 8, the following shall
apply:

                    (1) in the case of the issuance of shares of Common Stock
for cash, the consideration shall be the amount of such cash, provided that in
no case shall any deduction be made for any commissions, discounts or other
expenses incurred by the Company for any underwriting of the issue or otherwise
in connection therewith;

                                       26

<PAGE>

                    (2) in the case of the issuance of shares of Common Stock
for a consideration in whole or in part other than cash, the consideration other
than cash shall be deemed to be the fair market value thereof as determined in
good faith by the Board of Directors (irrespective of the accounting treatment
thereof), whose determination shall be conclusive, and described in a Board
resolution which shall be filed with the Warrant Agent;

                    (3) in the case of the issuance of securities convertible
into or exchangeable for shares, the aggregate consideration received therefor
shall be deemed to be the consideration received by the Company for the issuance
of such securities plus the additional minimum consideration, if any, to be
received by the Company upon the conversion or exchange thereof (the
consideration in each case to be determined in the same manner as provided in
clauses (1) and (2) of this subsection); and

                    (4) in the case of the issuance of shares of Common Stock
pursuant to rights, options or warrants which rights, options or warrants were
originally issued together with one or more other securities as part of a unit
at a price per unit, the consideration shall be deemed to be the fair value of
such rights, options or warrants at the time of issuance thereof as determined
in good faith by the Board of Directors whose determination shall be conclusive
and described in a Board resolution which shall be filed with the Warrant Agent
plus the additional minimum consideration, if any, to be received by the Company
upon the exercise, conversion or exchange thereof (as determined in the same
manner as provided in clauses (1) and (2) of this subsection).

               (g)  When De Minimis Adjustment May Be Deferred.

               No adjustment in the Exercise Price need be made unless the
adjustment would require an increase or decrease of at least 1% in the Exercise
Price; provided however, that any adjustments that are not made shall be carried
forward and taken into account in any subsequent adjustment. All calculations
under this Section 8 shall be made to the nearest cent or to the nearest
1/10,000th of a share, as the case may be, it being understood that no such
rounding shall be made under subsection (o).

               (h)  When No Adjustment Required.

               No adjustment need be made for a transaction referred to Section
8(a), (b), (c), (d), (e) or (f) hereof, if Warrant holders are to participate
(without being required to exercise their Warrants) in the transaction on a
basis and with notice that the Board of Directors determines to be fair and
appropriate in light of the basis and notice on which holders of Common Stock
participate in the transaction. No adjustment need be made for (i) rights to
purchase Common Stock pursuant to a Company plan for reinvestment of dividends
or interest (ii) a change in the par value or no par value of the Common Stock
or (iii) the issuance by the Company of warrants to the Initial Purchasers on or
about January 29, 2003. To the extent the Warrants become convertible into cash,
no adjustment need be made thereafter as to the cash. Interest will not accrue
on the cash. No adjustment shall be made pursuant to this Section 8 if such
adjustment causes the Exercise Price to fall below the par value per Warrant
Share.

               (i)  Notice of Adjustment.

               Whenever the Exercise Price is adjusted, the Company shall
provide the notices required by Section 10 hereof.

               (j)  Notice of Certain Transactions.

                                       27

<PAGE>

               If (i) the Company takes any action that would require an
adjustment in the Exercise Price pursuant to Section 8(a), (b), (c), (d), (e) or
(f) hereof and if the Company does not arrange for Warrant holders to
participate pursuant to Section 8(h) hereof, (ii) the Company takes any action
that would require a supplemental Warrant Agreement pursuant to Section 8(j)
hereof or (iii) there is a liquidation or dissolution of the Company, then the
Company shall mail to Warrant holders a notice stating the proposed record date
for a dividend or distribution or the proposed effective date of a subdivision,
combination, reclassification, consolidation, merger, transfer, lease,
liquidation or dissolution. The Company shall mail the notice at least 15 days
before such date. Failure to mail the notice or any defect in it shall not
affect the validity of the transaction.

               (k)  Reorganization of Company.

               Immediately after the date hereof, if the Company consolidates or
merges with or into, or transfers or leases all or substantially all its assets
to, any person, upon consummation of such transaction the Warrants shall
automatically become exercisable if such transaction occurs within the Exercise
Period for the kind and amount of securities, cash or other assets which the
holder of a Warrant would have owned immediately after the consolidation,
merger, transfer or lease if the holder had exercised the Warrant immediately
before the effective date of the transaction. Concurrently with the consummation
of such transaction, the corporation formed by or surviving any such
consolidation or merger if other than the Company, or the person to which such
sale or conveyance shall have been made, shall enter into (i) a supplemental
Warrant Agreement so providing and further providing for adjustments which shall
be as nearly equivalent as may be practical to the adjustments provided for in
this Section 8(k) and (ii) a supplement to the Warrant Registration Rights
Agreement providing for the assumption of the Company's obligations thereunder.
The successor Company shall mail to Warrant holders a notice describing the
supplemental Warrant Agreement and Warrant Registration Rights Agreement. If the
issuer of securities deliverable upon exercise of Warrants under the
supplemental Warrant Agreement is an affiliate of the formed, surviving,
transferee or lessee corporation, that issuer shall join in the supplemental
Warrant Agreement and Warrant Registration Rights Agreement. If this Section
8(k) applies, Sections 8(a), (b), (c), (d), (e) and (f) hereof do not apply.

               (l)  Company Determination Final.

               Any determination that the Company or the Board of Directors must
make pursuant to Section 8(a), (c), (d), (e), (f), (g), (h) or (i) hereof is
conclusive.

               (m)  Warrant Agent's Disclaimer.

               The Warrant Agent has no duty to determine when an adjustment
under this Section 8 should be made, how it should be made or what it should be.
The Warrant Agent has no duty to determine whether any provisions of a
supplemental Warrant Agreement under Section 8(k) hereof are correct. The
Warrant Agent makes no representation as to the validity or value of any
securities or assets issued upon exercise of Warrants. The Warrant Agent shall
not be responsible for the Company's failure to comply with this Section 8.

               (n)  When Issuance or Payment May Be Deferred.

               In any case in which this Section 8 shall require that an
adjustment in the Exercise Price be made effective as of a record date for a
specified event, the Company may elect to defer until the occurrence of such
event (i) issuing to the holder of any Warrant exercised after such record date
the Warrant Shares and other capital stock of the Company, if any, issuable upon
such exercise over and

                                       28

<PAGE>

above the Warrant Shares and other capital stock of the Company, if any,
issuable upon such exercise on the basis of the Exercise Price and (ii) paying
to such holder any amount in cash in lieu of a fractional share pursuant to
Section 10 hereof; provided that the Company shall deliver to such holder a due
bill or other appropriate instrument evidencing such holder's right to receive
such additional Warrant Shares, other capital stock and cash upon the occurrence
of the event requiring such adjustment.

               (o)  Adjustment in Number of Shares.

               Upon each adjustment of the Exercise Price pursuant to this
Section 8, each Warrant outstanding prior to the making of the adjustment in the
Exercise Price shall thereafter evidence the right to receive upon payment of
the adjusted Exercise Price that number of shares of Common Stock (calculated to
the nearest hundredth) obtained from the following formula:

               N' = N  X E
                        ---
                         E'
where:

               N'   =   the adjusted number of Warrant Shares issuable upon
                        exercise of a Warrant by payment of the adjusted
                        Exercise Price.

               N    =   the number or Warrant Shares previously issuable upon
                        exercise of a Warrant by payment of the Exercise Price
                        prior to adjustment.

               E'   =   the adjusted Exercise Price.

               E    =   the Exercise Price prior to adjustment.

               (p)  Form of Warrants.

               Irrespective of any adjustments in the Exercise Price or the
number or kind of shares purchasable upon the exercise of the Warrants, Warrants
theretofore or thereafter issued may continue to express the same price and
number and kind of shares as are stated in the Warrants initially issuable
pursuant to this Agreement.

SECTION 9.          FRACTIONAL INTERESTS.

               The Company shall not be required to issue fractional Warrant
Shares on the exercise of Warrants. If more than one Warrant shall be presented
for exercise in full at the same time by the same holder, the number of full
Warrant Shares which shall be issuable upon the exercise thereof shall be
computed on the basis of the aggregate number of Warrant Shares purchasable on
exercise of the Warrants so presented. If any fraction of a Warrant Share would,
except for the provisions of this Section 9, be issuable on the exercise of any
Warrants (or specified portion thereof), the Company shall pay an amount in cash
equal to the Fair Value per Warrant Share, as determined on the day immediately
preceding the date the Warrant is presented for exercise, multiplied by such
fraction, computed to the nearest whole U.S. cent.

                                       29

<PAGE>

SECTION 10.         NOTICES TO WARRANT HOLDERS.

               (a)  Upon any adjustment of the Exercise Price pursuant to
Section 8 hereof, the Company shall promptly thereafter (i) cause to be filed
with the Warrant Agent a certificate of a firm of independent public accountants
of recognized standing selected by the Board of Directors of the Company (who
may be the regular auditors of the Company) setting forth the Exercise Price
after such adjustment and setting forth in reasonable detail the method of
calculation and the facts upon which such calculations are based and setting
forth the number of Warrant Shares (or portion thereof) issuable after such
adjustment in the Exercise Price, upon exercise of a Warrant and payment of the
adjusted Exercise Price, which certificate shall be conclusive evidence of the
correctness of the matters set forth therein, and (ii) cause to be given to each
of the registered holders of Warrants at the address appearing on the Warrant
register for each such registered holder written notice of such adjustments by
first-class mail, postage prepaid. Where appropriate, such notice may be given
in advance and included as a part of the notice required to be mailed under the
other provisions of this Section 10.

               (b)  In case:

               (i)  the Company shall authorize the issuance to all holders of
        shares of Common Stock of rights, options or warrants to subscribe for
        or purchase shares of Common Stock or of any other subscription rights
        or warrants;

               (ii) the Company shall authorize the distribution to all holders
        of shares of Common Stock of evidences of its indebtedness or assets
        (other than dividends or cash distributions paid out of consolidated
        current or retained earnings as shown on the books of the Company
        prepared in accordance with generally accepted accounting principles or
        dividends payable in shares of Common Stock or distributions referred to
        in Section 10(a) hereof);

               (iii) of any consolidation or merger to which the Company is a
        party and for which approval of any stockholders of the Company is
        required, or of the conveyance or transfer of the properties and assets
        of the Company substantially as an entirety, or of any reclassification
        or change of Common Stock issuable upon exercise of the Warrants (other
        than a change in par value, or from par value to no par value, or from
        no par value to par value, or as a result of a subdivision or
        combination), or a tender offer or exchange offer for shares of Common
        Stock;

               (iv) of the voluntary or involuntary dissolution, liquidation or
        winding up of the Company; or

               (v)  the Company proposes to take any action (other than actions
        of the character described in Section 8(a) hereof) which would require
        an adjustment of the Exercise Price pursuant to Section 8 hereof;

then the Company shall cause to be filed with the Warrant Agent and shall cause
to be given to each of the registered holders of Warrants at his address
appearing on the Warrant register, at least 20 days (or 10 days in any case
specified in clauses (i) or (ii) above) prior to the applicable record date
hereinafter specified, or promptly in the case of events for which there is no
record date, by first-class mail, postage prepaid, a written notice stating (x)
the date as of which the holders of record of shares of Common Stock to be
entitled to receive any such rights, options, warrants or distribution are to be
determined, (y) the initial expiration date set forth in any tender offer or
exchange offer for shares of Common Stock, or (z) the date on which any such
consolidation, merger, conveyance, transfer, dissolution, liquidation or winding
up is expected to become effective or consummated, and the date as of which it
is expected that holders of record of shares of Common Stock shall be entitled
to exchange such shares for securities or other property, if any, deliverable
upon such reclassification, consolidation, merger, conveyance, transfer,

                                       30

<PAGE>

dissolution, liquidation or winding up. The failure to give the notice required
by this Section 11 or any defect therein shall not affect the legality or
validity of any distribution, right, option, warrant, consolidation, merger,
conveyance, transfer, dissolution, liquidation or winding up, or the vote upon
any action.

               (c)  Nothing contained in this Agreement or in any of the Warrant
        Certificates shall be construed as conferring upon the holders of
        Warrants the right to vote or to consent or to receive notice as
        stockholders in respect of the meetings of stockholders or the election
        of directors of the Company or any other matter, or any rights
        whatsoever as stockholders of the Company.

SECTION 11.         MERGER, CONSOLIDATION OR CHANGE OF NAME OF WARRANT AGENT.

               (g)  Any corporation into which the Warrant Agent may be merged
or with which it may be consolidated, or any corporation resulting from any
merger or consolidation to which the Warrant Agent shall be a party, or any
corporation succeeding to all or substantially all of the business of the
Warrant Agent, shall be the successor to the Warrant Agent hereunder without the
execution or filing of any paper or any further act on the part of any of the
parties hereto, provided that such corporation would be eligible for appointment
as a successor warrant agent under the provisions of Section 13 hereof. In case
at the time such successor to the Warrant Agent shall succeed to the agency
created by this Agreement, and in case at that time any of the Warrant
Certificates shall have been countersigned but not delivered, any such successor
to the Warrant Agent may adopt the countersignature of the original Warrant
Agent; and in case at that time any of the Warrant Certificates shall not have
been countersigned, any successor to the Warrant Agent may countersign such
Warrant Certificates either in the name of the predecessor Warrant Agent or in
the name of the successor to the Warrant Agent; and in all such cases such
Warrant Certificates shall have the full force and effect provided in the
Warrant Certificates and in this Agreement.

               (h)  In case at any time the name of the Warrant Agent shall be
changed and at such time any of the Warrant Certificates shall have been
countersigned but not delivered, the Warrant Agent whose name has been changed
may adopt the countersignature under its prior name, and in case at that time
any of the Warrant Certificates shall not have been countersigned, the Warrant
Agent may countersign such Warrant Certificates either in its prior name or in
its changed name, and in all such cases such Warrant Certificates shall have the
full force and effect provided in the Warrant Certificates and in this
Agreement.

SECTION 12.         WARRANT AGENT.

               The Warrant Agent undertakes only those duties and obligations
specifically imposed on it by this Agreement upon the following terms and
conditions, by all of which the Company and the holders of Warrants, by their
acceptance thereof, shall be bound:

               (a)  The statements contained herein and in the Warrant
Certificates shall be taken as statements of the Company and the Warrant Agent
assumes no responsibility for the correctness of any of the same except such as
describe the Warrant Agent or action taken or to be taken by it. The Warrant
Agent assumes no responsibility with respect to the distribution of the Warrant
Certificates except as herein otherwise provided.

                                       31

<PAGE>

               (b)  The Warrant Agent shall not be responsible for any failure
of the Company to comply with any of the covenants contained in this Agreement
or in the Warrant Certificates to be complied with by the Company.

               (c)  The Warrant Agent may consult at any time with counsel
satisfactory to it (who may be counsel for the Company) and the Warrant Agent
shall incur no liability or responsibility to the Company or to any holder of
any Warrant Certificate in respect of any action taken, suffered or omitted by
it hereunder in good faith and in accordance with the opinion or the advice of
such counsel.

               (d)  The Warrant Agent shall incur no liability or responsibility
to the Company or to any holder of any Warrant Certificate for any action taken
in reliance on any Warrant Certificate, certificate of shares, notice,
resolution, waiver, consent, order, certificate, or other paper, document or
instrument (whether in original or facsimile form) believed by it to be genuine
and to have been signed, sent or presented by the proper party or parties. The
Warrant Agent need not investigate any fact or matter stated in such document.

               (e)  The Company agrees to pay to the Warrant Agent reasonable
compensation for all services rendered by the Warrant Agent in the execution of
this Agreement, to reimburse the Warrant Agent for all expenses, taxes and
governmental charges and other charges of any kind and nature incurred by the
Warrant Agent in the execution of this Agreement. The Company shall indemnify
the Warrant Agent and its agents, employees, officers, directors and
shareholders for, and hold same harmless against, any and all losses,
liabilities, claims, damages or expenses (including without limitation
reasonable attorney's fees and expenses) incurred by it arising out of or in
connection with the acceptance or administration of its duties under this
Warrant Agreement, including the costs and expenses of enforcing this Warrant
Agreement against the Company and defending itself against any claim (whether
asserted by the Company or any Holder or any other person) or liability in
connection with the exercise or performance of any of its powers or duties
hereunder, except to the extent any such loss, liability or expense is
determined by a court of competent jurisdiction to have been cause by its gross
negligence or willful misconduct. The Warrant Agent shall notify the Company
promptly of any claim for which it may seek indemnity. Failure by the Warrant
Agent to so notify the Company shall not relieve the Company of its obligations
hereunder. At the Warrant Agent's sole discretion, the Company shall defend the
claim and the Warrant Agent shall cooperate in the defense at the Company's
expense. The Warrant Agent may have separate counsel and the Company shall pay
the reasonable fees and expenses of such counsel. The Company need not pay for
any settlement made without its consent, which consent shall not be unreasonably
withheld. The benefits of this Section shall survive termination of this
Agreement or change of Warrant Agent.

               (f)  The Warrant Agent shall be under no obligation to institute
any action, suit or legal proceeding or to take any other action likely to
involve expense unless the Company or one or more registered holders of Warrants
shall furnish the Warrant Agent with reasonable security and indemnity
satisfactory to it for any costs and expenses which may be incurred, but this
provision shall not affect the power of the Warrant Agent to take such action as
it may consider proper, whether with or without any such security or indemnity.
All rights of action under this Agreement or under any of the Warrants may be
enforced by the Warrant Agent without the possession of any of the Warrant
Certificates or the production thereof at any trial or other proceeding relative
thereto, and any such action, suit or proceeding instituted by the Warrant Agent
shall be brought in its name as Warrant Agent and any recovery of judgment shall
be for the ratable benefit of the registered holders of the Warrants, as their
respective rights or interests may appear.

                                       32

<PAGE>

               (g)  The Warrant Agent, and any stockholder, director, officer or
employee of it, may buy, sell or deal in any of the Warrants or other securities
of the Company or become pecuniarily interested in any transaction in which the
Company may be interested, or contract with or lend money to the Company or
otherwise act as fully and freely as though it were not Warrant Agent under this
Agreement. Nothing herein shall preclude the Warrant Agent from acting in any
other capacity for the Company or for any other legal entity.

               (h)  The Warrant Agent shall act hereunder solely as agent for
the Company, and its duties shall be determined solely by the provisions hereof.
The Warrant Agent shall not be liable for anything which it may do or refrain
from doing in connection with this Agreement except for its own gross negligence
or willful misconduct.

               (i)  The Warrant Agent shall not at any time be under any duty or
responsibility to any holder of any Warrant Certificate to make or cause to be
made any adjustment of the Exercise Price or number of the Warrant Shares or
other securities or property deliverable as provided in this Agreement, or to
determine whether any facts exist which may require any of such adjustments, or
with respect to the nature or extent of any such adjustments, when made, or with
respect to the method employed in making the same. The Warrant Agent shall not
be accountable with respect to the validity or value or the kind or amount of
any Warrant Shares or of any securities or property which may at any time be
issued or delivered upon the exercise of any Warrant or with respect to whether
any such Warrant Shares or other securities will when issued be validly issued
and fully paid and nonassessable, and makes no representation with respect
thereto.

               (i)  The Warrant Agent shall not be required to, and shall not,
expend or risk any of its own funds or otherwise incur any financial liability
in the performance of any of its duties hereunder.

               (j)  In no event shall the Warrant Agent be liable for any
consequential, punitive or special damages, or for the acts or omissions of its
nominees, correspondents, designees, subagents or subcustodians.

               (k)  The Warrant Agent shall not incur any liability for not
performing any act or fulfilling any duty, obligation or responsibility
hereunder by reason of any occurrence beyond the control of the Warrant Agent
(including but not limited to any act or provision of any present or future law
or regulation or governmental authority, any act of God or war, or the
unavailability of the Federal Reserve Bank wire or telex or other wire or
communication facility).

               (l)  In the event of any ambiguity or uncertainty hereunder or in
any notice, instruction or other communication received by the Warrant Agent
hereunder, the Warrant Agent may, in its sole discretion, refrain from taking
any action other than retain possession of the Warrant Shares, unless the
Warrant Agent receives written instructions, signed by the Company, which
eliminates such ambiguity or uncertainty.

SECTION 13.         CHANGE OF WARRANT AGENT.

               If the Warrant Agent shall become incapable of acting as Warrant
Agent, the Company shall appoint a successor to such Warrant Agent. If the
Company shall fail to make such appointment within a period of 30 days after it
has been notified in writing of such incapacity by the Warrant Agent or

                                       33

<PAGE>

by the registered holder of a Warrant Certificate, then the registered holder of
any Warrant or the Warrant Agent may petition at the expense of the Company to
any court of competent jurisdiction for the appointment of a successor to the
Warrant Agent. Pending appointment of a successor to such Warrant Agent, either
by the Company or by such a court, the duties of the Warrant Agent shall be
carried out by the Company. The holders of a majority of the unexercised
Warrants shall be entitled at any time to remove the Warrant Agent and appoint a
successor to such Warrant Agent. Such successor to the Warrant Agent need not be
approved by the Company or the former Warrant Agent. After appointment the
successor to the Warrant Agent shall be vested with the same powers, rights,
duties and responsibilities as if it had been originally named as Warrant Agent
without further act or deed; provided that the former Warrant Agent shall
deliver and transfer to the successor to the Warrant Agent any property at the
time held by it hereunder and execute and deliver any further assurance,
conveyance, act or deed necessary for the purpose. Failure to give any notice
provided for in this Section 13, however, or any defect therein, shall not
affect the legality or validity of the appointment of a successor to the Warrant
Agent.

SECTION 14.         REPORTS.

               (a)  Whether or not required by the rules and regulations of the
Commission, so long as any Warrants or the Warrant Shares are outstanding, the
Company shall make available to the Warrant Agent and the holders of Warrants or
Warrant Shares (i) all quarterly and annual financial information that would be
required to be contained in a filing with the Commission on Forms 10-Q and 10-K
if the Company were required to file such Forms, including a "Management's
Discussion and Analysis of Financial Condition and Results of Operations" and,
with respect to the annual information only, a report thereon by the Company's
certified independent accountants and (ii) all current reports that would be
required to be filed with the Commission on Form 8-K if the Company were
required to file such reports. In addition, whether or not required by the rules
and regulations of the Commission, the Company shall file a copy of all such
information and reports with the Commission for public availability (unless the
Commission shall not accept such a filing) and make such information available
to securities analysts and prospective investors upon request. Delivery of such
reports, information and documents to the Warrant Agent is for informational
purposes only and the Warrant Agent's receipt of such shall not constitute
constructive notice of any information contained therein or determinable from
information contained therein, including the Company's compliance with any of
its covenants hereunder (as to which the Warrant Agent is entitled to rely
exclusively on Officers' Certificates).

               (b)  The Company shall provide the Warrant Agent with a
sufficient number of copies of all such reports that the Warrant Agent may be
required to deliver to the holders of the Warrants and the Warrant Shares under
this Section 14.

SECTION 15.         NOTICES TO COMPANY AND WARRANT AGENT.

               Any notice or demand authorized by this Agreement to be given or
made by the Warrant Agent or by the registered holder of any Warrant to or on
the Company shall be sufficiently given or made when received if deposited in
the mail, first class or registered, postage prepaid, addressed (until another
address is filed in writing by the Company with the Warrant Agent) as follows:

                          American Tower Corporation
                          116 Huntington Avenue, 11th Floor
                          Boston, MA 02116
                          Telecopier No.: (617) 375-7575
                          Attention: Chief Financial Officer and Treasurer and

                                       34

<PAGE>

                          Executive Vice President and General Counsel

                 With a copy to:

                    Palmer & Dodge LLP
                    111 Huntington Avenue
                    Boston, MA 02199
                    Telecopier No.: (617) 227-4420
                    Attention: Matthew J. Gardella, Esq.

               In case the Company shall fail to maintain such office or agency
or shall fail to give such notice of the location or of any change in the
location thereof, presentations may be made and notices and demands may be
served at the principal office of the Warrant Agent.

               Any notice pursuant to this Agreement to be given by the Company
or by the registered holder(s) of any Warrant to the Warrant Agent shall be
sufficiently given when and if deposited in the mail, first-class or registered,
postage prepaid, addressed (until another address is filed in writing by the
Warrant Agent with the Company) to the Warrant Agent as follows:

                 The Bank of New York
                 101 Barclay Street, Fl. 8W
                 New York, NY 10286
                 Telecopier No.: (212) 815-5704
                 Attention: Corporate Trust Administration

SECTION 16.         SUPPLEMENTS AND AMENDMENTS.

               The Company and the Warrant Agent may from time to time
supplement or amend this Agreement without the approval of any holders of
Warrants in order to cure any ambiguity or to correct or supplement any
provision contained herein which may be defective or inconsistent with any other
provision herein, or to make any other provisions in regard to matters or
questions arising hereunder which the Company and the Warrant Agent may deem
necessary or desirable and which shall not in any way adversely affect the
interests of the holders of Warrants. Any amendment or supplement to this
Agreement that has an adverse effect on the interests of the holders of Warrants
shall require the written consent of the holders of a majority of the then
outstanding Warrants (excluding Warrants held by the Company or any of its
affiliates). The consent of each holder of Warrants affected shall be required
for any amendment pursuant to which the Exercise Price would be increased or the
number of Warrant Shares purchasable upon exercise of Warrants would be
decreased (other than pursuant to adjustments provided in this Agreement).

SECTION 17.         SUCCESSORS.

               All the covenants and provisions of this Agreement by or for the
benefit of the Company or the Warrant Agent shall bind and inure to the benefit
of their respective successors and assigns hereunder.

                                       35

<PAGE>

SECTION 18.         TERMINATION.

               This Agreement shall terminate at 5:00 p.m., New York City time
on August 1, 2008. Notwithstanding the foregoing, this Agreement will terminate
on any earlier date if all Warrants have been exercised or on the Redemption
Date if the Escrow Corp. Merger has not been consummated. The provisions of
Section 12 shall survive such termination.

SECTION 19.         GOVERNING LAW.

               This Agreement and each Warrant Certificate issued hereunder
shall be deemed to be a contract made under the laws of the State of New York
and for all purposes shall be construed in accordance with the internal laws of
said State.

SECTION 20.         BENEFITS OF THIS AGREEMENT.

               Nothing in this Agreement shall be construed to give to any
person or corporation other than the Company, the Warrant Agent and the
registered holders of Warrants any legal or equitable right, remedy or claim
under this Agreement; but this Agreement shall be for the sole and exclusive
benefit of the Company, the Warrant Agent and the registered holders of
Warrants.

SECTION  21.        COUNTERPARTS.

               This Agreement may be executed in any number of counterparts and
each of such counterparts shall for all purposes be deemed to be an original,
and all such counterparts shall together constitute but one and the same
instrument.

                            [Signature Page Follows]

                                       36

<PAGE>

               IN WITNESS WHEREOF, the parties hereto have caused this Agreement
to be duly executed, as of the day and year first above written.

                                American Tower Corporation

                                By: /s/ Bradley E. Singer
                                   -----------------------------------------
                                    Name: Bradley E. Singer
                                    Title: Chief Financial Officer and Treasurer

                                The Bank of New York, as Warrant Agent

                                By: /s/ Kisha A. Holder
                                   -----------------------------------------
                                    Name: Kisha A. Holder
                                    Title: Assistant Treasurer

                                       37

<PAGE>

                                    EXHIBIT A

                          [Form of Warrant Certificate]

                                     [Face]

               Unit Legend. Each Warrant issued prior to the Separation Date
shall bear the following legend (the "Unit Legend") on the face thereof:

THE WARRANTS EVIDENCED BY THIS CERTIFICATE ARE INITIALLY ISSUED AS PART OF AN
ISSUANCE OF UNITS (THE "UNITS"), EACH OF WHICH CONSISTS OF $1,000 PRINCIPAL
AMOUNT AT MATURITY OF THE 12.25% SENIOR SUBORDINATED DISCOUNT NOTES DUE 2008
(THE "NOTES") OF ESCROW CORP. AND ONE WARRANT TO PURCHASE 14.0953 SHARES, PAR
VALUE $0.01 PER SHARE, OF AMERICAN TOWER CORPORATION.

PRIOR TO THE EARLIEST TO OCCUR OF (I) 180 DAYS AFTER THE CLOSING OF THE
OFFERING, (II) THE DATE ON WHICH A REGISTRATION STATEMENT FOR A REGISTERED
EXCHANGE OFFER WITH RESPECT TO THE NOTES IS DECLARED EFFECTIVE UNDER THE
SECURITIES ACT, (III) THE DATE A SHELF REGISTRATION STATEMENT WITH RESPECT TO
THE WARRANTS IS DECLARED EFFECTIVE UNDER THE SECURITIES ACT, (IV) SUCH DATE AS
CREDIT SUISSE FIRST BOSTON LLC IN ITS SOLE DISCRETION SHALL DETERMINE AND (V) IN
THE EVENT OF A CHANGE OF CONTROL, THE DATE AMERICAN TOWER ESCROW CORPORATION (OR
ITS SUCCESSOR) MAILS THE REQUISITE NOTICE TO THE HOLDERS, THE WARRANTS EVIDENCED
BY THIS CERTIFICATE MAY NOT BE TRANSFERRED OR EXCHANGED SEPARATELY FROM, BUT MAY
BE TRANSFERRED OR EXCHANGED ONLY TOGETHER WITH, THE NOTES.

               Private Placement Legend: Each Warrant issued pursuant to an
exemption from the registration requirements of the Securities Act shall bear
the following legend (the "Private Placement Legend") on the face thereof:

THIS SECURITY (OR ITS PREDECESSOR) AND THE WARRANT SHARES TO BE ISSUED UPON ITS
EXERCISE WAS ORIGINALLY ISSUED IN A TRANSACTION EXEMPT FROM REGISTRATION UNDER
THE UNITED STATES SECURITIES ACT OF 1933 (THE "SECURITIES ACT"). ACCORDINGLY,
THIS SECURITY MAY NOT BE OFFERED, SOLD OR OTHERWISE TRANSFERRED IN THE ABSENCE
OF SUCH REGISTRATION OR AN APPLICABLE EXEMPTION THEREFROM. EACH PURCHASER OF
THIS SECURITY IS HEREBY NOTIFIED THAT THE SELLER OF THIS SECURITY MAY BE RELYING
ON THE EXEMPTION FROM THE PROVISIONS OF SECTION 5 OF THE SECURITIES ACT PROVIDED
BY RULE 144A THEREUNDER.

THE HOLDER OF THIS SECURITY AGREES FOR THE BENEFIT OF THE COMPANY THAT (A) THIS
SECURITY MAY BE OFFERED, RESOLD, PLEDGED OR OTHERWISE TRANSFERRED, ONLY (I) IN
THE UNITED STATES TO A PERSONWHOM THE SELLER REASONABLY BELIEVES IS A QUALIFIED
INSTITUTIONAL BUYER (AS DEFINED IN RULE 144A UNDER THE SECURITIES ACT) IN A
TRANSACTION MEETING THE REQUIREMENTS OF RULE 144A, (II) OUTSIDE THE UNITED
STATES IN AN OFFSHORE TRANSACTION IN ACCORDANCE WITH RULE 904 UNDER THE
SECURITIES ACT, (III) PURSUANT TO AN EXEMPTION FROM REGISTRATION UNDER THE
SECURITIES ACT PROVIDED BY RULE 144 THEREUNDER (IF

                                        1

<PAGE>

AVAILABLE) OR (IV) PURSUANT TO AN EFFECTIVE REGISTRATION STATEMENT UNDER THE
SECURITIES ACT, IN EACH OF CASES (I) THROUGH (IV) IN ACCORDANCE WITH ANY
APPLICABLE SECURITIES LAWS OF ANY STATE OF THE UNITED STATES, AND (B) THE
HOLDERWILL, AND EACH SUBSEQUENT HOLDER IS REQUIRED TO, NOTIFY ANY PURCHASER OF
THIS WARRANT FROM IT OF THE RESALE RESTRICTIONS REFERRED TO IN (A) ABOVE.

THE HOLDER OF THIS SECURITY AGREES NOT TO ENGAGE IN HEDGING TRANSACTIONS UNLESS
IN COMPLIANCE WITH THE SECURITIES ACT AND (4) AGREES THAT IT WILL DELIVER TO
EACH PERSON TO WHOM THIS SECURITY OR AN INTEREST HEREIN IS TRANSFERRED A NOTICE
SUBSTANTIALLY TO THE EFFECT OF THIS LEGEND.

AS USED HEREIN, THE TERMS "OFFSHORE TRANSACTION" AND "UNITED STATES" HAVE THE
MEANINGS GIVEN TO THEM BY RULE 902 OF REGULATION S UNDER THE SECURITIES ACT. THE
WARRANT AGREEMENT CONTAINS A PROVISION REQUIRING THE WARRANT AGENT TO REFUSE TO
REGISTER ANY TRANSFER OF THIS SECURITY IN VIOLATION OF THE FOREGOING.

               Global Warrant Legend. Each Global Warrant shall bear the
following legend (the "Global Warrant Legend") on the face thereof:

THIS GLOBAL WARRANT IS HELD BY THE DEPOSITARY (AS DEFINED IN THE WARRANT
AGREEMENT GOVERNING THIS WARRANT) OR ITS NOMINEE IN CUSTODY FOR THE BENEFIT OF
THE BENEFICIAL OWNERS HEREOF, AND IS NOT TRANSFERABLE TO ANY PERSON UNDER ANY
CIRCUMSTANCES EXCEPT THAT (I) THE WARRANT AGENT MAY MAKE SUCH NOTATIONS HEREON
AS MAY BE REQUIRED PURSUANT TO SECTION 3.5 OF THE WARRANT AGREEMENT, (II) THIS
GLOBAL WARRANT MAY BE EXCHANGED IN WHOLE BUT NOT IN PART PURSUANT TO SECTION
3.5(A) OF THE WARRANT AGREEMENT, (III) THIS GLOBAL WARRANT MAY BE DELIVERED TO
THE WARRANT AGENT FOR CANCELLATION PURSUANT TO SECTION 3.8 OF THE WARRANT
AGREEMENT AND (IV) THIS GLOBAL WARRANT MAY BE TRANSFERRED TO A SUCCESSOR
DEPOSITARY WITH THE PRIOR WRITTEN CONSENT OF AMERICAN TOWER CORPORATION (THE
"COMPANY").

               Regulation S Legend. Each Warrant that is a Registrable Security
and issued pursuant to Regulation S shall bear the following legend (the
"Regulation S Legend") on the face thereof:

THIS WARRANT AND THE SECURITIES TO BE ISSUED UPON ITS EXERCISE HAVE NOT BEEN
REGISTERED UNDER THE SECURITIES ACT AND THE WARRANT MAY NOT BE EXERCISED BY OR
ON BEHALF OF ANY U.S. PERSON UNLESS REGISTERED UNDER THE U.S. SECURITIES ACT OF
1933, AS AMENDED (THE "SECURITIES ACT") OR AN EXEMPTION FROM SUCH REGISTRATION
IS AVAILABLE. IN ORDER TO EXERCISE THIS WARRANT, THE HOLDER MUST FURNISH TO THE
COMPANY AND THE WARRANT AGENT EITHER (A) A WRITTEN CERTIFICATION THAT IT IS NOT
A U.S. PERSON AND THE WARRANT IS NOT BEING EXERCISED ON BEHALF OF A U.S. PERSON
OR (B) A WRITTEN OPINION OF COUNSEL TO THE EFFECT THAT THE SECURITIES DELIVERED
UPON EXERCISE OF THE WARRANT HAVE BEEN REGISTERED UNDER THE SECURITIES ACT OR
THAT THE DELIVERY OF SUCH SECURITIES IS EXEMPT FROM THE REGISTRATION
REQUIREMENTS

                                        2

<PAGE>

OF THE SECURITIES ACT. TERMS IN THIS LEGEND HAVE THE MEANINGS GIVEN TO THEM BY
REGULATION S UNDER THE SECURITIES ACT.

                                        3

<PAGE>

No. ___________    ___Warrants
CUSIP No. ________

                               Warrant Certificate

                           AMERICAN TOWER CORPORATION

               This Warrant Certificate certifies that Cede & Co., or its
registered assigns, is the registered holder of Warrants expiring August 1, 2008
(the "Warrants") to purchase Class A Common Stock, par value $0.01 (the "Common
Stock"), of American Tower Corporation, a Delaware corporation. Each Warrant
entitles the registered holder upon exercise at any time on or after the opening
of business on January 29, 2006 until 5:00 p.m., New York City time before or on
August 1, 2008 (the "Exercise Period), to receive from the Company 14.0953 fully
paid and nonassessable shares of Common Stock (the "Warrant Shares") at the
initial exercise price (the "Exercise Price") of $0.01 per share payable upon
surrender of this Warrant Certificate and payment of the Exercise Price at the
office or agency of the Warrant Agent, but only subject to the conditions set
forth herein and in the Warrant Agreement referred to on the reverse hereof. The
Exercise Price and number of Warrant Shares issuable upon exercise of the
Warrants are subject to adjustment upon the occurrence of certain events set
forth in the Warrant Agreement. Notwithstanding the foregoing, if the Escrow
Corp. Merger has not been consummated and the Notes have been mandatorily
redeemed pursuant to Section 3.08 of the Indenture (the "Redemption Date"), each
Warrant shall become void and all rights thereunder and all rights in respect
thereof under this Agreement shall cease as of the Redemption Date.

               No Warrant may be exercised after 5:00 p.m., New York City time
on August 1, 2008, and to the extent not exercised by such time such Warrants
shall become void.

               Reference is hereby made to the further provisions of this
Warrant Certificate set forth on the reverse hereof and such further provisions
shall for all purposes have the same effect as though fully set forth at this
place.

               This Warrant Certificate shall not be valid unless countersigned
by the Warrant Agent, as such term is used in the Warrant Agreement.

               This Warrant Certificate shall be governed by and construed in
accordance with the internal laws of the State of New York.

                                        1

<PAGE>

                  IN WITNESS WHEREOF, the Company has caused this Warrant
Certificate to be signed below.

Dated: January 29, 2003

                           American Tower Corporation

                           By:
                               ----------------------------------------------
                               Name:  Bradley E. Singer
                               Title: Chief Financial Officer and Treasurer

Countersigned:

The Bank of New York
as Warrant Agent

By:
    --------------------------
    Name:  Kisha A. Holder
    Title: Assistant Treasurer

                                        2

<PAGE>

                        [Reverse of Warrant Certificate]

               The Warrants evidenced by this Warrant Certificate are part of a
duly authorized issue of Warrants expiring at 5:00 p.m. New York City time on
August 1, 2008 entitling the holder upon exercise to receive shares of Class A
Common Stock, and are issued or to be issued pursuant to a Warrant Agreement
dated as of January 29, 2003 (the "Warrant Agreement"), duly executed and
delivered by the Company to The Bank of New York, as warrant agent (the "Warrant
Agent"), which Warrant Agreement is hereby incorporated by reference in and made
a part of this instrument and is hereby referred to for a description of the
rights, limitation of rights, obligations, duties and immunities thereunder of
the Warrant Agent, the Company and the holders (the words "holders" or "holder"
meaning the registered holders or registered holder) of the Warrants. A copy of
the Warrant Agreement may be obtained by the holder hereof upon written request
to the Company.

               Warrants may be exercised at any time on or after the opening of
business on January 29, 2006 and on or before 5:00 p.m. New York City time on
August 1, 2008; provided that holders shall be able to exercise their Warrants
only if a registration statement relating to the Warrants Shares is then in
effect, or the exercise of such Warrants is exempt from the registration
requirements of the Securities Act of 1933, as amended (the "Securities Act"),
and such securities are qualified for sale or exempt from qualification under
the applicable securities laws of the states in which the various holders of the
Warrants or other persons to whom it is proposed that the Warrant Shares be
issued on exercise of the Warrants reside. In order to exercise all or any of
the Warrants represented by this Warrant Certificate, the holder must deliver to
the Warrant Agent at its New York corporate trust office set forth in Section 15
of the Warrant Agreement this Warrant Certificate and the form of election to
purchase on the reverse hereof duly filled in and signed, which signature shall
be medallion guaranteed by an institution which is a member of a Securities
Transfer Association recognized signature guarantee program, and upon payment to
the Warrant Agent for the account of the Company of the Exercise Price, as
adjusted as provided in the Warrant Agreement, for the number of Warrant Shares
in respect of which such Warrants are then exercised. No adjustment shall be
made for any dividends on any Common Stock issuable upon exercise of this
Warrant. Notwithstanding the foregoing, if the Escrow Corp. Merger has not been
consummated and the Notes have been mandatorily redeemed pursuant to Section
3.08 of the Indenture (the "Redemption Date"), each Warrant shall become void
and all rights thereunder and all rights in respect thereof under this Agreement
shall cease as of the Redemption Date.

               The Warrant Agreement provides that upon the occurrence of
certain events the Exercise Price set forth on the face hereof may, subject to
certain conditions, be adjusted. If the Exercise Price is adjusted, the Warrant
Agreement provides that the number of shares of Common Stock issuable upon the
exercise of each Warrant shall be adjusted. No fractions of a share of Common
Stock will be issued upon the exercise of any Warrant, but the Company will pay
the cash value thereof determined as provided in the Warrant Agreement.

                  The Company has agreed pursuant to a Warrant Registration
Rights Agreement dated as of January 29, 2003 (the "Warrant Registration Rights
Agreement") to file within 90 days after the issuance of the Warrants and use
its reasonable best efforts to make effective, subject to certain exceptions
detailed in the Warrant Registration Rights Agreement, on or before 180 days
after such date a shelf registration statement covering the resale of the
Warrants, the issuance by American Tower Corporation's common stock upon the
exercise of the warrants resold pursuant to such registration statement and the
resale of the Warrant Shares by the holder thereof on the appropriate form under
the Securities Act, and to use its reasonable best efforts (subject to certain
"black-out" periods not to exceed 60 days in any calendar year subject to
extension for 30 days in certain circumstances) to keep such

                                       A-1

<PAGE>

registration statement continuously effective under the Securities Act, subject
to certain exceptions, until two years following the Closing Date.

               Warrant Certificates, when surrendered at the office of the
Warrant Agent by the registered holder thereof in person or by legal
representative or attorney duly authorized in writing, may be exchanged, in the
manner and subject to the limitations provided in the Warrant Agreement, but
without payment of any service charge, for another Warrant Certificate or
Warrant Certificates of like tenor evidencing in the aggregate a like number of
Warrants.

               Upon due presentation for registration of transfer of this
Warrant Certificate at the office of the Warrant Agent a new Warrant Certificate
or Warrant Certificates of like tenor and evidencing in the aggregate a like
number of Warrants shall be issued to the transferee(s) in exchange for this
Warrant Certificate, subject to the limitations provided in the Warrant
Agreement, without charge except for any tax or other governmental charge
imposed in connection therewith.

               The Company and the Warrant Agent may deem and treat the
registered holder(s) thereof as the absolute owner(s) of this Warrant
Certificate (notwithstanding any notation of ownership or other writing hereon
made by anyone), for the purpose of any exercise hereof, of any distribution to
the holder(s) hereof, and for all other purposes, and neither the Company nor
the Warrant Agent shall be affected by any notice to the contrary. Neither the
Warrants nor this Warrant Certificate entitles any holder hereof to any rights
of a stockholder of the Company.

                                       A-2

<PAGE>

                         [Form of Election to Purchase]

                    (To Be Executed Upon Exercise Of Warrant)

               The undersigned hereby irrevocably elects to exercise the right,
represented by this Warrant Certificate, to receive _____________ shares of
Class A Common Stock and herewith tenders payment for such shares to the order
of AMERICAN TOWER CORPORATION in the amount of $__________ in accordance with
the terms hereof. The undersigned requests that a certificate for such shares be
registered in the name of _______________, whose address is __________________
and that such shares be delivered to ___________, whose address is
____________________________. If said number of shares is less than all of the
shares of Common Stock purchasable hereunder, the undersigned requests that a
new Warrant Certificate representing the remaining balance of such shares be
registered in the name of ______________________, whose address is
____________________, and that such Warrant Certificate be delivered to whose
address is ____________________.

                                        ----------------------------------------
                                        Signature

Date:

                                        ----------------------------------------
                                        Signature Guaranteed

Signatures must be guaranteed by an "eligible guarantor institution" meeting the
requirements of the Warrant Agent, which requirements include membership or
participation in the Security Transfer Agent Medallion Program ("STAMP") or such
other "signature guarantee program" as may be determined by the Warrant Agent in
addition to, or in substitution for, STAMP, all in accordance with the
Securities Exchange Act of 1934, as amended.

                                       A-3

<PAGE>

              SCHEDULE OF EXCHANGES OF INTERESTS OF GLOBAL WARRANTS

The following exchanges of a part of this Global Warrant have been made:

<TABLE>
<CAPTION>
                                                                       Number of Warrants
                      Amount of decrease                                 in this Global
                         in Number of        Amount of increase in      Warrant following        Signature of
                       warrants in this      Number of Warrants in       such decrease or     authorized officer
Date of Exchange        Global Warrant        this Global Warrant            increase          of Warrant Agent
------------------   --------------------   -----------------------   --------------------   --------------------
<S>                       <C>                    <C>                     <C>                    <C>

</TABLE>

                                       A-4

<PAGE>

                                    EXHIBIT B

                         FORM OF CERTIFICATE OF TRANSFER

American Tower Corporation
116 Huntington Avenue, 11th Floor
Boston, MA 02116
Attention: [________]

The Bank of New York
[_______________]
[_______________]
Attention: [__________]

           Re: Warrants

               Reference is hereby made to the Warrant Agreement, dated as of
January 29, 2003 (the "Warrant Agreement"), between American Tower Corporation,
as issuer (the "Company"), and The Bank of New York, as warrant agent.
Capitalized terms used but not defined herein shall have the meanings given to
them in the Warrant Agreement.

               ___________________, (the "Transferor") owns and proposes to
transfer the Warrant[s] or interest in such Warrant[s] specified in Annex A
hereto, in the principal amount at maturity of $___________ in such Warrant[s]
or interests (the "Transfer"), to ___________________________ (the
"Transferee"), as further specified in Annex A hereto. In connection with the
Transfer, the Transferor hereby certifies that:

                             [CHECK ALL THAT APPLY]

               1.   [ ] Check if Transferee will take delivery of a beneficial
interest in the 144A Global Warrant or a Definitive Warrant Pursuant to Rule
144A. The Transfer is being effected pursuant to and in accordance with Rule
144A under the United States Securities Act of 1933, as amended (the "Securities
Act"), and, accordingly, the Transferor hereby further certifies that the
beneficial interest or Definitive Warrant is being transferred to a Person that
the Transferor reasonably believed and believes is purchasing the beneficial
interest or Definitive Warrant for its own account, or for one or more accounts
with respect to which such Person exercises sole investment discretion, and such
Person and each such account is a "qualified institutional buyer" within the
meaning of Rule 144A in a transaction meeting the requirements of Rule 144A and
such Transfer is in compliance with any applicable blue sky securities laws of
any state of the United States. Upon consummation of the proposed Transfer in
accordance with the terms of the Warrant Agreement, the transferred beneficial
interest or Definitive Warrant will be subject to the restrictions on transfer
enumerated in the Private Placement Legend printed on the 144A Global Warrant
and/or the Definitive Warrant and in the Warrant Agreement and the Securities
Act.

               2.   [ ] Check if Transferee will take delivery of a beneficial
interest in the Regulation S Global Warrant or a Definitive Warrant pursuant to
Regulation S. The Transfer is being effected pursuant to and in accordance with
Rule 903 or Rule 904 under the Securities Act and, accordingly, the Transferor
hereby further certifies that (i) the Transfer is not being made to a person in
the United States and (x) at the time the buy order was originated, the
Transferee was outside the United

                                       B-1

<PAGE>

States or such Transferor and any Person acting on its behalf reasonably
believed and believes that the Transferee was outside the United States or (y)
the transaction was executed in, on or through the facilities of a designated
offshore securities market and neither such Transferor nor any Person acting on
its behalf knows that the transaction was prearranged with a buyer in the United
States, (ii) no directed selling efforts have been made in contravention of the
requirements of Rule 903(b) or Rule 904(b) of Regulation S under the Securities
Act, (iii) the transaction is not part of a plan or scheme to evade the
registration requirements of the Securities Act and (iv) if the proposed
transfer is being made prior to the expiration of the Restricted Period, the
transfer is not being made to a U.S. Person or for the account or benefit of a
U.S. Person (other than an Initial Purchaser). Upon consummation of the proposed
transfer in accordance with the terms of the Warrant Agreement, the transferred
beneficial interest or Definitive Warrant will be subject to the restrictions on
Transfer enumerated in the Private Placement Legend printed on the Regulation S
Global Warrant and/or the Definitive Warrant and in the Warrant Agreement and
the Securities Act.

               3.   [ ] Check and complete if Transferee will take delivery of a
beneficial interest in the IAI Global Warrant or a Definitive Warrant pursuant
to any provision of the Securities Act other than Rule 144A or Regulation S. The
Transfer is being effected in compliance with the transfer restrictions
applicable to beneficial interests in Restricted Global Warrants and Restricted
Definitive Warrants and pursuant to and in accordance with the Securities Act
and any applicable blue sky securities laws of any state of the United States,
and accordingly the Transferor hereby further certifies that (check one):

        (a) [ ] such Transfer is being effected pursuant to and in accordance
        with Rule 144 under the Securities Act;

                                       or

        (b) [ ] such Transfer is being effected to the Company or a subsidiary
        thereof;

                                       or

        (c) [ ] such Transfer is being effected pursuant to an effective
        registration statement under the Securities Act and in compliance with
        the prospectus delivery requirements of the Securities Act;

                                       or

        (d) [ ] such Transfer is being effected to an Institutional Accredited
        Investor and pursuant to an exemption from the registration requirements
        of the Securities Act other than Rule 144A, Rule 144 or Rule 904, and
        the Transferor hereby further certifies that it has not engaged in any
        general solicitation within the meaning of Regulation D under the
        Securities Act and the Transfer complies with the transfer restrictions
        applicable to beneficial interests in a Restricted Global Warrant or
        Restricted Definitive Warrants and the requirements of the exemption
        claimed, which certification is supported by (1) a certificate executed
        by the Transferee in the form of Exhibit D to the Warrant Agreement and
        (2) if the Company requests, an Opinion of Counsel provided by the
        Transferor or the Transferee (a copy of which the Transferor has
        attached to this certification), to the effect that such Transfer is in
        compliance with the Securities Act. Upon consummation of the proposed
        transfer in accordance with the terms of the Warrant Agreement, the
        transferred beneficial interest or Definitive Warrant will be subject to
        the restrictions on transfer enumerated in the Private Placement Legend
        printed on the IAI Global Warrant and/or the Definitive Warrants and in
        the Warrant Agreement and the Securities Act.

                                       B-2

<PAGE>

               4.   [ ] Check if Transferee will take delivery of a beneficial
interest in an Unrestricted Global Warrant or of an Unrestricted Definitive
Warrant.

        (a) [ ] Check if Transfer is pursuant to Rule 144. (i) The Transfer is
        being effected pursuant to and in accordance with Rule 144 under the
        Securities Act and in compliance with the transfer restrictions
        contained in the Warrant Agreement and any applicable blue sky
        securities laws of any state of the United States and (ii) the
        restrictions on transfer contained in the Warrant Agreement and the
        Private Placement Legend are not required in order to maintain
        compliance with the Securities Act. Upon consummation of the proposed
        Transfer in accordance with the terms of the Warrant Agreement, the
        transferred beneficial interest or Definitive Warrant will no longer be
        subject to the restrictions on transfer enumerated in the Private
        Placement Legend printed on the Restricted Global Warrants, on
        Restricted Definitive Warrants and in the Warrant Agreement.

        (b) [ ] Check if Transfer is Pursuant to Regulation S. (i) The Transfer
        is being effected pursuant to and in accordance with Rule 903 or Rule
        904 under the Securities Act and in compliance with the transfer
        restrictions contained in the Warrant Agreement and any applicable blue
        sky securities laws of any state of the United States and (ii) the
        restrictions on transfer contained in the Warrant Agreement and the
        Private Placement Legend are not required in order to maintain
        compliance with the Securities Act. Upon consummation of the proposed
        Transfer in accordance with the terms of the Warrant Agreement, the
        transferred beneficial interest or Definitive Warrant will no longer be
        subject to the restrictions on transfer enumerated in the Private
        Placement Legend printed on the Restricted Global Warrants, on
        Restricted Definitive Warrants and in the Warrant Agreement.

        (c) [ ] Check if Transfer is Pursuant to Other Exemption. (i) The
        Transfer is being effected pursuant to and in compliance with an
        exemption from the registration requirements of the Securities Act other
        than Rule 144, Rule 903 or Rule 904 and in compliance with the transfer
        restrictions contained in the Warrant Agreement and any applicable blue
        sky securities laws of any State of the United States and (ii) the
        restrictions on transfer contained in the Warrant Agreement and the
        Private Placement Legend are not required in order to maintain
        compliance with the Securities Act. Upon consummation of the proposed
        Transfer in accordance with the terms of the Warrant Agreement, the
        transferred beneficial interest or Definitive Warrant will not be
        subject to the restrictions on transfer enumerated in the Private
        Placement Legend printed on the Restricted Global Warrants or Restricted
        Definitive Warrants and in the Warrant Agreement.

               This certificate and the statements contained herein are made for
your benefit and the benefit of the Company.

                                          --------------------------------------
                                                [Insert Name of Transferor]

                                          By:
                                             ----------------------------------
                                             Name:
                                             Title:

Dated:
       -------------------------------------

                                       B-3

<PAGE>

                       ANNEX A TO CERTIFICATE OF TRANSFER

1. The Transferor owns and proposes to transfer the following:

                            [CHECK ONE OF (a) OR (b)]

          (a) [ ] a beneficial interest in the:

              (i)   [ ] 144A Global Warrant, or

              (ii)  [ ] Regulation S Global Warrant, or

              (iii) [ ] IAI Global Warrant; or

          (b) [ ] a Restricted Definitive Warrant.

2. After the Transfer the Transferee will hold:

                                   [CHECK ONE]

          (a) [ ] a beneficial interest in the:

              (i)   [ ] 144A Global Warrant, or

              (ii)  [ ] Regulation S Global Warrant, or

              (iii) [ ] IAI Global Warrant, or

              (iv)  [ ] Unrestricted Global Warrant; or

          (b) [ ] a Restricted Definitive Warrant; or

          (c) [ ] an Unrestricted Definitive Warrant,

          in accordance with the terms of the Warrant Agreement.

                                       B-4

<PAGE>

                                    EXHIBIT C
                         FORM OF CERTIFICATE OF EXCHANGE

American Tower Corporation
116 Huntington Avenue, 11th Floor
Boston, MA 02116
Attention: [________]

The Bank of New York
[_____________]

[_____________]
Attention: [__________]

         Re:  Warrants

                              (CUSIP ____________)

               Reference is hereby made to the Warrant Agreement, dated as of
January 29, 2003 (the "Warrant Agreement"), between American Tower Corporation,
as issuer (the "Company"), and The Bank of New York, as warrant agent.
Capitalized terms used but not defined herein shall have the meanings given to
them in the Warrant Agreement.

               __________________________, (the "Owner") owns and proposes to
exchange the Warrant[s] or interest in such Warrant[s] specified herein, in the
amount of $____________ in such Warrant[s] or interests (the "Exchange"). In
connection with the Exchange, the Owner hereby certifies that:

               1. Exchange of Restricted Definitive Warrants or Beneficial
Interests in a Restricted Global Warrant for Unrestricted Definitive Warrants or
Beneficial Interests in an Unrestricted Global Warrant

        (a) [ ] Check if Exchange is from beneficial interest in a Restricted
        Global Warrant to beneficial interest in an Unrestricted Global Warrant.
        In connection with the Exchange of the Owner's beneficial interest in a
        Restricted Global Warrant for a beneficial interest in an Unrestricted
        Global Warrant in an equal principal amount, the Owner hereby certifies
        (i) the beneficial interest is being acquired for the Owner's own
        account without transfer, (ii) such Exchange has been effected in
        compliance with the transfer restrictions applicable to the Global
        Warrants and pursuant to and in accordance with the United States
        Securities Act of 1933, as amended (the "Securities Act"), (iii) the
        restrictions on transfer contained in the Warrant Agreement and the
        Private Placement Legend are not required in order to maintain
        compliance with the Securities Act and (iv) the beneficial interest in
        an Unrestricted Global Warrant is being acquired in compliance with any
        applicable blue sky securities laws of any state of the United States.

        (b) [ ] Check if Exchange is from beneficial interest in a Restricted
        Global Warrant to Unrestricted Definitive Warrant. In connection with
        the Exchange of the Owner's beneficial interest in a Restricted Global
        Warrant for an Unrestricted Definitive Warrant, the Owner hereby
        certifies (i) the Definitive Warrant is being acquired for the Owner's
        own account without transfer,

                                       C-1

<PAGE>

        (ii) such Exchange has been effected in compliance with the transfer
        restrictions applicable to the Restricted Global Warrants and pursuant
        to and in accordance with the Securities Act, (iii) the restrictions on
        transfer contained in the Warrant Agreement and the Private Placement
        Legend are not required in order to maintain compliance with the
        Securities Act and (iv) the Definitive Warrant is being acquired in
        compliance with any applicable blue sky securities laws of any state of
        the United States.

        (c) [ ] Check if Exchange is from Restricted Definitive Warrant to
        beneficial interest in an Unrestricted Global Warrant. In connection
        with the Owner's Exchange of a Restricted Definitive Warrant for a
        beneficial interest in an Unrestricted Global Warrant, the Owner hereby
        certifies (i) the beneficial interest is being acquired for the Owner's
        own account without transfer, (ii) such Exchange has been effected in
        compliance with the transfer restrictions applicable to Restricted
        Definitive Warrants and pursuant to and in accordance with the
        Securities Act, (iii) the restrictions on transfer contained in the
        Warrant Agreement and the Private Placement Legend are not required in
        order to maintain compliance with the Securities Act and (iv) the
        beneficial interest is being acquired in compliance with any applicable
        blue sky securities laws of any state of the United States.

        (d) [ ] Check if Exchange is from Restricted Definitive Warrant to
        Unrestricted Definitive Warrant. In connection with the Owner's Exchange
        of a Restricted Definitive Warrant for an Unrestricted Definitive
        Warrant, the Owner hereby certifies (i) the Unrestricted Definitive
        Warrant is being acquired for the Owner's own account without transfer,
        (ii) such Exchange has been effected in compliance with the transfer
        restrictions applicable to Restricted Definitive Warrants and pursuant
        to and in accordance with the Securities Act, (iii) the restrictions on
        transfer contained in the Warrant Agreement and the Private Placement
        Legend are not required in order to maintain compliance with the
        Securities Act and (iv) the Unrestricted Definitive Warrant is being
        acquired in compliance with any applicable blue sky securities laws of
        any state of the United States.

               2.   Exchange of Restricted Definitive Warrants or Beneficial
Interests in Restricted Global Warrants for Restricted Definitive Warrants or
Beneficial Interests in Restricted Global Warrants

        (a) [ ] Check if Exchange is from beneficial interest in a Restricted
        Global Warrant to Restricted Definitive Warrant. In connection with the
        Exchange of the Owner's beneficial interest in a Restricted Global
        Warrant for a Restricted Definitive Warrant in a number equal to the
        number of beneficial interests exchanged, the Owner hereby certifies
        that the Restricted Definitive Warrant is being acquired for the Owner's
        own account without transfer. Upon consummation of the proposed Exchange
        in accordance with the terms of the Warrant Agreement, the Restricted
        Definitive Warrant issued will continue to be subject to the
        restrictions on transfer enumerated in the Private Placement Legend
        printed on the Restricted Definitive Warrant and in the Warrant
        Agreement and the Securities Act.

        (b) Check if Exchange is from Restricted Definitive Warrant to
        beneficial interest in a Restricted Global Warrant. In connection with
        the Exchange of the Owner's Restricted Definitive Warrant for a
        beneficial interest in the [CHECK ONE] [ ] 144A Global Warrant, [ ]
        Regulation S Global Warrant, [ ] IAI Global Warrant in a number equal to
        the number of beneficial interests exchanged, the Owner hereby certifies
        (i) the beneficial interest is being acquired for the Owner's own
        account without transfer and (ii) such Exchange has been effected in
        compliance with the transfer restrictions applicable to the Restricted
        Global Warrants and pursuant to and in

                                       C-2

<PAGE>

        accordance with the Securities Act, and in compliance with any
        applicable blue sky securities laws of any state of the United States.
        Upon consummation of the proposed Exchange in accordance with the terms
        of the Warrant Agreement, the beneficial interest issued will be subject
        to the restrictions on transfer enumerated in the Private Placement
        Legend printed on the relevant Restricted Global Warrant and in the
        Warrant Agreement and the Securities Act.

               This certificate and the statements contained herein are made for
your benefit and the benefit of the Company.

                                          --------------------------------------
                                                [Insert Name of Transferor]

                                          By:
                                             -----------------------------------
                                              Name:
                                              Title:

Dated:
       -------------------------------------

                                       C-3

<PAGE>

                                    EXHIBIT D
                            FORM OF CERTIFICATE FROM
                   ACQUIRING INSTITUTIONAL ACCREDITED INVESTOR

American Tower Corporation
116 Huntington Avenue, 11th Floor
Boston, MA 02116
Attention: [________]

The Bank of New York
[_______________]
[_______________]
Attention: [__________]

         Re: Warrants

               Reference is hereby made to the Warrant Agreement, dated as of
January 29, 2003 (the "Warrant Agreement"), between American Tower Corporation,
as issuer (the "Company"), and The Bank of New York, as warrant agent.
Capitalized terms used but not defined herein shall have the meanings given to
them in the Warrant Agreement.

               In connection with our proposed purchase of $____________ amount
of:

     (a) [ ] a beneficial interest in a Global Warrant, or

     (b) [ ] a Definitive Warrant,

               we confirm that:

               1.   We understand that any subsequent transfer of the Warrants
or any interest therein is subject to certain restrictions and conditions set
forth in the Warrant Agreement and the undersigned agrees to be bound by, and
not to resell, pledge or otherwise transfer the Warrants or any interest therein
except in compliance with, such restrictions and conditions and the United
States Securities Act of 1933, as amended (the "Securities Act").

               2.   We understand that the offer and sale of the Warrants have
not been registered under the Securities Act, and that the Warrants and any
interest therein may not be offered or sold except as permitted in the following
sentence. We agree, on our own behalf and on behalf of any accounts for which we
are acting as hereinafter stated, that if we should sell the Warrants or any
interest therein, we will do so only (A) to the Company or any subsidiary
thereof, (B) in accordance with Rule 144A under the Securities Act to a
"qualified institutional buyer" (as defined therein), (C) to an institutional
"accredited investor" (as defined below) that, prior to such transfer, furnishes
(or has furnished on its behalf by a U.S. broker-dealer) to you and to the
Company a signed letter substantially in the form of this letter and, if
requested by the Company, an Opinion of Counsel in form reasonably acceptable to
the Company to the effect that such transfer is in compliance with the
Securities Act, (D) outside the United States in accordance with Rule 904 of
Regulation S under the Securities Act, (E) pursuant to the provisions of Rule
144(k) under the Securities Act or (F) pursuant to an effective registration
statement under the Securities Act, and we further agree to provide to any
person purchasing the Definitive Warrant

                                       D-1

<PAGE>

or beneficial interest in a Global Warrant from us in a transaction meeting the
requirements of clauses (A) through (E) of this paragraph a notice advising such
purchaser that resales thereof are restricted as stated herein.

               3.   We understand that, on any proposed resale of the Warrants
or beneficial interest therein, we will be required to furnish to you and the
Company such certifications, legal opinions and other information as you and the
Company may reasonably require to confirm that the proposed sale complies with
the foregoing restrictions. We further understand that the Warrants purchased by
us will bear a legend to the foregoing effect.

               4.   We are an institutional "accredited investor" (as defined in
Rule 501(a)(1), (2), (3) or (7) of Regulation D under the Securities Act) and
have such knowledge and experience in financial and business matters as to be
capable of evaluating the merits and risks of our investment in the Warrants,
and we and any accounts for which we are acting are each able to bear the
economic risk of our or its investment.

               5.   We are acquiring the Warrants or beneficial interest therein
purchased by us for our own account or for one or more accounts (each of which
is an institutional "accredited investor") as to each of which we exercise sole
investment discretion.

               We agree not to engage in any hedging transactions with regard to
the Warrants unless such hedging transactions are in compliance with the
Securities Act.

               You and the Company are entitled to rely upon this letter and are
irrevocably authorized to produce this letter or a copy hereof to any interested
party in any administrative or legal proceedings or official inquiry with
respect to the matters covered hereby.

                                          --------------------------------------
                                                [Insert Name of Transferor]

                                          By:
                                             -----------------------------------
                                             Name:
                                             Title:

Dated:
       -------------------------------------

                                       D-2

<PAGE>

                                    EXHIBIT E

                  FORM OF WARRANT REGISTRATION RIGHTS AGREEMENT

                                       E-1

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