Document:

<PAGE>

                                                                     EXHIBIT 4.3

                          FIRST AMENDED AND RESTATED
                             EMPLOYMENT AGREEMENT
                              (ROBIN P. RITCHIE)

          THIS FIRST AMENDED AND RESTATED EMPLOYMENT AGREEMENT (the "Amended
Agreement") is made effective as of January 1, 2000 (the "Effective Date"), by
and between APPLIED VOICE RECOGNITION, INC., a Delaware corporation
("Employer"), and ROBIN P. RITCHIE, an individual residing in Harris County,
Texas ("Employee").

                                 W I T N E S S E T H:

          WHEREAS, Employer, as successor by merger of Applied Voice
Recognition, Inc., originally a Utah corporation, and Employee executed that
certain Employment Agreement dated effective as of July 1, 1997 (the
"Agreement");

          WHEREAS, prior to Employee's termination, Employer and Employee orally
agreed to allow any remaining salary payments due to Employee under the
Agreement to be paid in common stock of the Company at the Employee's option;
and

          WHEREAS, Employer and Employee now desire to amend and restate the
Agreement pursuant to the terms and provisions set forth herein.

          NOW, THEREFORE, for and in consideration of the premises and the
mutual covenants contained herein, and other good and valuable consideration,
the receipt and sufficiency of which is hereby acknowledged, and intending to be
legally bound hereby, the parties hereby covenant and agree to modify and
restate the Agreement as follows:

          1. EMPLOYMENT. Employer hereby employs Employee and Employee hereby
accepts employment with Employer on the terms and conditions set forth in this
Amended Agreement.

          2. TERM OF EMPLOYMENT. The term of Employee's employment hereunder
(the "Term") shall commence as of August 1, 1998 (the "Commencement Date") and
shall continue (subject to termination by either Employer or Employee as
hereinafter provided) for an initial term (the "Initial Term") expiring on July
31, 2002 (the "Expiration Date"). The Expiration Date shall be automatically
extended unless terminated by Employer or Employee for successive one year
periods following the expiration of the Initial Term. If Employer desires to
terminate Employee's employment under this Amended Agreement at the end of the
Initial Term or at the end of any succeeding one year term, Employer shall give
written notice of such desire to Employee at least one month prior to the
expiration of the Initial Term or any succeeding one year term. If Employee
desires to terminate Employee's employment under this Amended Agreement at the
end of the Initial Term or at the end of any succeeding one year term, Employee
shall give written notice of such desire to Employer at least one month prior to
the expiration of the Initial Term or any

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succeeding one year term. At the expiration of the then existing term, Employer
shall have no further obligation to Employee other than payment of earned and
unpaid Base Salary (as hereafter defined) and bonuses under Sections 3(a) and
3(b), respectively, and Employee shall have no further obligation to Employer
except as set forth in Sections 7, 8, 9 and 10.

  3.  COMPENSATION AND OTHER BENEFITS.

          a. As compensation for all services rendered by Employee in
performance of Employee's duties or obligations under this Amended Agreement,
Employer shall pay Employee a monthly base salary of TWELVE THOUSAND FIVE
HUNDRED AND 00/100 DOLLARS ($12,500.00) (the "Base Salary"). Employee's Base
Salary shall be payable in equal semi-monthly installments or in the manner and
on the timetable which Employer's payroll is customarily handled or at such
intervals as Employer and Employee may hereafter agree to from time to time.
Employer agrees to review Employee's performance on a quarterly basis and to
consider an increase in Employee's Base Salary on an annual basis, beginning on
the first anniversary of the Commencement Date. Employee's salary may, but is
not required to, be increased from time to time, based upon Employee's
performance and other relevant factors, as Employer may deem appropriate,
without affecting any other provisions of this Amended Agreement.

          b. In addition to receiving the Base Salary provided for in Section
3(a), for the portion of the calendar year beginning with the Commencement Date
and each calendar year thereafter during the Term hereof, Employee shall be
entitled to a bonus of up to $100,000 per year (or pro rata for portions of a
year) if, and only if, Employee has met the performance criteria set by Employer
for the applicable year. In connection therewith, Employer agrees that by
September 1, 1998 and by January 31 of each year thereafter, it shall set the
performance criteria for Employee's bonus to be earned during the applicable
year and shall communicate such criteria to Employee in writing. If Employee
successfully meets the performance criteria established by Employer (in the
discretion of Employer), Employer shall pay to Employee the bonus within thirty
(30) days of the end of the applicable year.

          c. Employee shall be entitled to be reimbursed by Employer for all
reasonable and necessary expenses incurred by Employee in carrying out
Employee's duties under this Amended Agreement in accordance with Employer's
standard policies regarding such reimbursements.

          d. Beginning within thirty (30) days of the Commencement Date,
Employee shall be entitled during the Term, upon satisfaction of all eligibility
requirements, if any, to participate in all health, dental, disability, life
insurance and other benefit programs now or hereafter established by Employer
which cover substantially all other of Employer's employees and shall receive
such other benefits as may be approved from time to time by Employer.

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<PAGE>

          e. Employee shall be entitled to receive two weeks of paid vacation
for each year during the Term following the first anniversary of the
Commencement Date and shall be entitled to receive paid holidays as enjoyed by
all other employees of Employer.

          4.   DUTIES.

          a. Employee is employed to act as Chief Operating Officer of the
Employer and in such other office or position as shall be assigned to Employee
from time to time by Employer, and to perform such duties as are commensurate
with Employee's position with Employer.

          b. Employee agrees that during the period of employment, Employee
shall devote full-time efforts to Employee's duties as an employee of Employer
and Employee shall use Employee's best efforts to perform the duties of
Employee's position in an efficient and competent manner and shall use
Employee's best efforts to promote the interests of Employer and any affiliated
companies.

          c. During the period of employment, Employee agrees not to (i) solely
or jointly with others undertake or join any planning for or organization of any
business activity competitive with the business activities of Employer, and (ii)
directly or indirectly, engage or participate in any other activities in
conflict with the best interests of Employer.

          d. Employee agrees that during the period of employment Employee shall
refer to Employer all opportunities in the computer industry related to voice
recognition software designs and applications to which Employee might become
exposed in carrying out Employee's duties and responsibilities hereunder.

          5.   STOCK OPTION PLAN.  As a further inducement to Employee to accept
employment upon the terms set forth herein and in consideration of Employee's
execution of this Amended Agreement, Employee shall be granted options entitling
Employee to purchase 300,000 shares of Employer's common stock, par value $0.001
(the "Options"), pursuant to, and Employee shall be entitled to otherwise
participate in, that certain Applied Voice Recognition, Inc. 1997 Incentive
Plan, as amended from time to time.  The granting instrument for the Options
will provide, in addition to other terms set forth therein, that (i) the
purchase price for the Options shall be the average bid and ask price for
Employer's shares of common stock on the NASDAQ OTCBB (or any national
securities exchange hereafter listing Employer's common stock) on the day prior
to the Commencement Date, and (ii) one fourth (1/4th) of the Options (being
options to purchase 75,000 shares) will vest on the first anniversary date of
the Commencement Date, and one thirty-sixth (1/36th) of the remaining Options
(being options to purchase 6,250 shares) will vest on the last day of each month
following the first anniversary date of the Commencement Date

          6.   TERMINATION OF EMPLOYMENT.  Employee's employment and this
Amended Agreement shall terminate upon the earliest to occur of any of the
following events (the actual date of such termination being referred to herein
as the "Termination Date"):

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               a. The termination of the Amended Agreement pursuant to Section
        2.

               b. Employee's employment pursuant hereto shall terminate in the
        event of the death of Employee.

               c. Employer may terminate Employee's employment under this
        Amended Agreement for cause without any prior notice (except as set
        forth in subparagraph (3) below), upon the occurrence of any of the
        following events:

                    (1) any embezzlement or wrongful diversion of funds of
          Employer or any affiliate of Employer by Employee;

                    (2) gross malfeasance by Employee in the conduct of
          Employee's duties;

                    (3) breach of this Amended Agreement and the failure to cure
          such breach following reasonable notice thereof;

                    (4) gross neglect by Employee in carrying out Employee's
          duties; or

                    (5) the failure of Employee to be able to perform Employee's
          duties hereunder for a period of not less than ninety (90) days by
          reason of disability. For purposes of this Amended Agreement, Employee
          shall be deemed to have become disabled when the Board of Directors of
          Employer, upon the advice of a qualified physician, shall have
          determined that Employee has become physically or mentally incapable
          (excluding infrequent and temporary absences due to ordinary illness)
          of performing Employee's duties under this Amended Agreement.  Before
          making any termination decision pursuant to this Section 6(c)(5), the
          Board of Directors of Employer shall determine whether there is any
          reasonable accommodation (within the meaning of the Americans with
          Disabilities Act) which would enable Employee to perform the essential
          functions of Employee's position under this Amended Agreement despite
          the existence of any such disability.  If such a reasonable
          accommodation is possible, Employer shall make that accommodation and
          shall not terminate Employee's employment hereunder based on such
          disability.

          d. If Employee's employment is terminated for any of the reasons
specified in Section 6, Employer shall no longer be obligated to make the
payments specified under Section 3 or to pay to Employee any other compensation
or benefits whatsoever, except as may otherwise be provided in Section 6(e).
Notwithstanding the foregoing, if for any reason Employee's employment is
terminated hereunder, any salary or bonus payable under Sections 3(a) or 3(b)
which shall have been earned but not yet paid shall be paid by Employer to
Employee or Employee's estate, as the case may be.

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          e. Employer shall have the right to terminate Employee's employment
hereunder without prior notice and without cause; provided, however, in such
event, Employee shall continue to receive his Base Salary for six (6) months
following the date of such termination or, at the Employee's Option, any amount
of the severance may be paid to Employee in shares of the Company's common
stock, par value $.001 per share (the "Common Stock"), at a 35% discount to the
Nasdaq Over-the-Counter Bulletin Board closing bid price on the day before the
filing of a Form S-8 covering such shares of Common Stock. If this Amended
Agreement is terminated by Employer under this Section 6(e), any Options that
would otherwise vest on or before the next vesting period (be it annual or
monthly) shall automatically become fully vested immediately upon termination;
however, any additional unvested Options shall be cancelled upon termination.
Notwithstanding the foregoing, the prior provisions of this Section 6(e) shall
be void and of no force or effect in the event of (i) the sale of substantially
all of the assets of Employer, (ii) the merger of Employer into another entity,
or (iii) the merger of another entity into Employer if, as a result of any
transaction described in clause (i), (ii) or (iii), the shareholders of Employer
do not control a majority of the shares of the surviving entity. In the event of
any such sale or merger, any of the Options that have not yet vested shall
immediately vest.

          7.   INVENTIONS AND CREATIONS BELONG TO EMPLOYER.

          a. Any and all inventions, discoveries, improvements or creations
(collectively, "Creations") which Employee has conceived or made or may conceive
or make during the period of employment in any way, directly or indirectly,
connected with Employer's business shall be the sole and exclusive property of
Employer. Employee agrees that all copyrightable works created by Employee or
under Employer's direction in connection with Employer's business are "works
made for hire" and shall be the sole and complete property of Employer and that
any and all copyrights to such works shall belong to Employer. To the extent any
of the works described in the preceding sentence are not deemed to be "works
made for hire," Employee hereby assigns all proprietary rights, including
copyright, in these works to Employer without further compensation.

          b. Employee further agrees to (i) disclose promptly to Employer all
such Creations which Employee has made or may make solely, jointly or commonly
with others during the period of employment to the extent connected with
Employer's business, (ii) assign all such Creations to Employer, and (iii)
execute and sign any and all applications, assignments or other instruments
which Employer may deem necessary in order to enable Employer, at Employer's
expense, to apply for, prosecute and obtain copyrights, patents or other
proprietary rights in the United States and foreign countries or in order to
transfer to Employer all right, title and interest in said Creations.

          8.   CONFIDENTIALITY; OWNERSHIP OF INFORMATION.  Employer promises
that Employer will, during the Term, provide Employee with access to such
Confidential Information (as defined in Section 8(a)) owned by Employer and that
is used in the operation of Employer's business as reasonably necessary to allow
Employee to perform Employee's obligations hereunder.  Employee acknowledges
that Employer has agreed to provide Employee with a definite term of

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employment and with access to such Confidential Information of Employer during
that term of employment.

          a. DEFINITION. For purposes of this Amended Agreement, "Confidential
Information" means any and all information relating directly or indirectly to
Employer that is not generally ascertainable from public or published
information or trade sources and that represents proprietary information to
Employer, excluding, however, (i) Employees' business contacts, (ii) information
already known to Employee prior to Employee's employment with Employer, and
(iii) information required to be divulged in any legal or administrative
proceeding in which Employee is involved. Confidential Information shall consist
of, for example, and not intending to be inclusive, (A) software (source and
object codes), algorithms, computer processing systems, techniques,
methodologies, formulae, processes, compilations of information, drawings,
proposals, job notes, reports, records and specifications, and (B) information
concerning any matters relating to the business of Employer, any of its
customers, prospective customers, customer contacts, licenses, the prices it
obtains or has obtained for the licensing of its software products and services,
or any other information concerning the business of Employer and Employer's good
will.

          b. NO DISCLOSURE. During the Term and at all times thereafter,
Employee shall not disclose or use in any manner, directly or indirectly, and
shall use Employee's best efforts and shall take all reasonable precautions to
prevent the disclosure of, any such trade secrets or other Confidential
Information, except to the extent required in the performance of Employee's
duties or obligations to Employer hereunder or by express prior written consent
of a duly authorized officer or director of Employer (other than Employee).

          c. OWNERSHIP OF INFORMATION. Such Confidential Information is and
shall remain the sole and exclusive property and proprietary information of
Employer or Employer's customers, as the case may be, and is disclosed in
confidence by Employer or permitted to be acquired from such customers in
reliance on Employee's Amended Agreement to maintain such Confidential
Information in confidence and not to use or disclose such Confidential
Information to any other person except in furtherance of Employer's business.

          d. RETURN OF MATERIAL. Upon the expiration or earlier termination of
this Amended Agreement for any reason, Employee shall immediately turn over to
Employer all documents, disks or other magnetic media, or other material in
Employee's possession or under Employee's control that (i) may contain or be
derived from Creations or Confidential Information, or (ii) are connected with
or derived from Employee's services to Employer. Employee shall not retain any
Confidential Information in any form (e.g., computer hard drive, microfilm,
etc.) upon the expiration or earlier termination of this Amended Agreement.

          9.   NONCOMPETE; WORKING FOR COMPETITOR.  In consideration of
Employee's employment by Employer, Employee will not, at any time during the
Term or at any time for twenty-four (24) months subsequent to any termination of
Employee's employment pursuant to the provisions of Section 6(c) or the
voluntary termination of employment by Employee pursuant to

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Section 2, directly or indirectly, within the United States, Canada, Mexico,
South America or Europe, for Employee's own account or on behalf of any direct
competitors of Employer, engage in any business or transaction involving the
design, installation, integration, service or consulting with respect to voice
recognition software designs and applications (whether as an employee, employer,
independent contractor, consultant, agent, principal, partner, stockholder,
corporate officer, director or in any other individual or representative
capacity), without the prior written consent of Employer, which consent may be
withheld by Employer in Employer's sole and absolute discretion.

          10.  NON-SOLICITATION OF EMPLOYEES.  During the Term and for a period
of twenty-four (24) months after the date of termination of employment, Employee
will not in any way, directly or indirectly (i) induce or attempt to induce any
employee of Employer to quit employment with Employer; (ii) otherwise interfere
with or disrupt Employer's relationship with its employees; (iii) solicit,
entice or hire away any employee of Employer; or (iv) hire or engage any
employee of Employer or any former employee of Employer whose employment with
Employer ceased less than one year before the date of such hiring or engagement.
Employee acknowledges that any attempt on the part of Employee to induce others
to leave Employer's employ, or any effort by Employee to interfere with
Employer's relationship with its other employees would be harmful and damaging
to Employer.

          11.  EMPLOYEE'S ACKNOWLEDGEMENT.  It is the express intention of
Employee and Employer to comply with sections 15.50 et seq. of the Texas
Business and Commerce Code in effect as of the date of execution hereof.
Employee stipulates that the provisions of this Amended Agreement are not
oppressive or overly burdensome to Employee and will not prevent Employee from
earning an income following termination of this Amended Agreement.  Employee
warrants and represents that:

          a. Employee is familiar with non-compete and non-solicitation
covenants;

          b. Employee has discussed or acknowledges the opportunity to discuss
the provisions of the non-compete and non-solicitation covenants contained
herein with Employee's attorney and has concluded that such provisions
(including, without limitation, the right to equitable relief and the length of
time provided for herein) are fair, reasonable and just under the circumstances;

          c. Employee is fully aware of the obligations, limitations and
liabilities included in the non-compete and non-solicitation covenants contained
in this Amended Agreement;

          d. The scope of activities covered hereby are substantially similar to
those activities to be performed by Employee under this Amended Agreement;

          e. The twenty-four (24) month non-compete and non-solicitation period
is a reasonable restriction, giving consideration to the following factors: (1)
Employee and Employer reasonably anticipate that this Amended Agreement,
although terminable under certain

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provisions, will continue in effect for sufficient duration to allow Employee to
attain superior bargaining strength and an ability for unfair competition with
respect to the customers covered hereby; (2) the duration of the twenty-four
(24) month non-compete and non-solicitation period is a reasonably necessary
period to allow Employer to restore its position of equivalent bargaining
strength and fair competition with respect to those customers covered hereby;
and (3) historically, employees of all types have remained with Employee for a
duration of longer than the duration of the twenty-four (24) month non-compete
and non-solicitation period; and

          f. The limitations contained in this Amended Agreement with respect to
geographic area, duration and scope of activity are reasonable; however, if any
court shall determine that the geographic area, duration or scope of activity of
any restriction contained in this Amended Agreement is unenforceable, it is the
intention of the parties that such restrictive covenants set forth herein shall
not thereby be terminated, but shall be deemed amended to the extent required to
render such covenants valid and enforceable.

          12.  REMEDIES; INJUNCTION.  In the event of a breach or threatened
breach by Employee of any of the provisions of this Amended Agreement, Employee
agrees that Employer, in addition to and not in limitation of any other rights,
remedies or damages available to Employer at law or in equity, shall be entitled
to a permanent injunction without the necessity of proving actual monetary loss
in order to prevent or restrain any such breach by Employee or by Employee's
partners, agents, representatives, servants, employees and/or any and all
persons directly or indirectly acting for or with Employee.  It is expressly
understood between the parties that this injunctive or other equitable relief
shall not be Employer's exclusive remedy for any breach of this Amended
Agreement, and Employer shall be entitled to seek any other relief or remedy
which it may have by contract, statute, law or otherwise for any breach hereof.

          13.  ARBITRATION.  The parties agree that all disputes or questions
arising in connection with this Amended Agreement and/or the termination of
Employee's employment hereunder shall be settled by a single arbitrator pursuant
to the rules of the American Arbitration Association in the City of Houston,
Texas, and the award of the arbitrators shall be final, non-appealable,
conclusive and enforceable in a court of competent jurisdiction; provided,
however, notwithstanding the foregoing, in no event shall any dispute, claim or
this Amended Agreement arising under Sections 7, 8, 9 and 10 of this Amended
Agreement that requires injunctive or other equitable relief be required to be
submitted to arbitration pursuant to this provision or otherwise.

          14.  NOTICES.  Any notice, demand or request which may be permitted,
required or desired to be given in connection therewith shall be given in
writing and directed to Employer and Employee as follows:

          If to Employer, at:       Applied Voice Recognition, Inc.
                                    1717 St. James Place, Suite 242
                                    Houston, Texas  77056
                                    Attention:  Chairman
                                    Facsimile No.:  (713) 621-7059

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          with a copy to:           Boyar, Simon & Miller
                                    4265 San Felipe, Suite 1200
                                    Houston, Texas  77027
                                    Attention:  Gary W. Miller, Esq.
                                    Facsimile No.:  (713) 552-1758

          or, if to Employee, at:   Mr. Robin P. Ritchie
                                    1611 Wild Rye Trail
                                    Sugar Land, Texas 77479

Notices shall be deemed properly delivered and received when and if either:  (i)
personally delivered; (ii) delivered by nationally-recognized overnight courier;
(iii) when deposited in the U.S. Mail, by registered or certified mail, return
receipt requested, postage prepaid; or (iv) sent via facsimile transmission with
confirmation mailed by regular U.S. mail.  Any party may change its notice
address for purposes hereof to any address within the continental United States
by giving written notice of such change to the other parties hereto at least
fifteen days prior to the intended effective date of such change.

          15.  SEVERABILITY.  If any provision of this Amended Agreement is
rendered or declared illegal or unenforceable by reason of any existing or
subsequently enacted legislation or by decree of a court of last resort,
Employer and Employee shall promptly meet and negotiate substitute provisions
for those rendered or declared illegal or unenforceable, but all the remaining
provisions of this Amended Agreement shall remain in full force and effect.

          16.  ASSIGNMENT.  This Amended Agreement may not be assigned by any
party without the prior written consent of the other parties.

          17.  BINDING AMENDED AGREEMENT.  This Amended Agreement shall be
binding upon and shall inure to the benefit of the parties hereto, and their
respective legal representatives, heirs, successors and permitted assigns.

          18.  GOVERNING LAW.  This Amended Agreement shall be governed by and
construed in accordance with the laws of the State of Texas.

          19.  ATTORNEYS FEES.  In the event of any dispute between the parties
regarding this Amended Agreement, the prevailing party shall be entitled to be
reimbursed for such prevailing party's attorneys fees and costs of court by the
non-prevailing party.

          20.  AMENDED AGREEMENT READ, UNDERSTOOD AND FAIR.  Employee has
carefully read and considered all provisions of this Amended Agreement and
agrees that all of the restrictions set forth are fair and reasonable and are
reasonably required for the protection of the interests of Employer.

                  (Remainder of Page Intentionally Left Blank)

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          IN WITNESS WHEREOF, the parties have executed this Amended Agreement
on this 14th day of February, 2000, effective as of the Effective Date.

                              EMPLOYER:

                              APPLIED VOICE RECOGNITION, INC.,
                               a Delaware corporation

                              By:  /s/ Timothy J. Connolly
                                   -----------------------
                              Timothy J. Connolly, Chairman

                              EMPLOYEE:

                               /s/ Robin P. Ritchie
                             ----------------------
                              ROBIN P. RITCHIE

                               Signature Page to
                          First Amended and Restated
                             Employment Agreement
                              (Robin P. Ritchie)

                                       10--------------------------------------------------------------------------------
--------------------------------------------------------------------------------

                           AMERICAN TOWER CORPORATION

                              THE BANK OF NEW YORK

                                     Trustee

                      ------------------------------------

                                    Indenture

                          Dated as of February 15, 2000

                      ------------------------------------

                                  $400,000,000

                   (subject to increase to up to $450,000,000
                         in the event and to the extent
                             an option is exercised)

                         5.0% Convertible Notes Due 2010

--------------------------------------------------------------------------------
--------------------------------------------------------------------------------

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<TABLE>
<CAPTION>
                                             TABLE OF CONTENTS

                                                                                                 Page

<S>                                                                                              <C>
PARTIES.............................................................................................1

RECITALS

         Authorization of Indenture.................................................................1
         Compliance with Legal Requirements.........................................................1
         Purpose of and Consideration for Indenture.................................................1

                                   ARTICLE ONE

                                   DEFINITIONS

         SECTION 1.1  Certain Terms Defined.........................................................1
                  Affiliate.........................................................................2
                  Agent.............................................................................2
                  Board of Directors................................................................2
                  Board Resolution..................................................................2
                  Business Day......................................................................2
                  Capital Stock.....................................................................3
                  Cash Equivalents..................................................................3
                  Change in Control.................................................................3
                  Change in Control Repurchase Date.................................................3
                  Change in Control Repurchase Price................................................3
                  Class A Common Stock..............................................................4
                  Closing Date......................................................................4
                  Common Stock......................................................................4
                  Conversion Agent..................................................................4
                  Conversion Price..................................................................4
                  Corporate Trust Office............................................................4
                  Date of Conversion................................................................4
                  Depositary........................................................................4
                  Disposition.......................................................................4
                  DTC...............................................................................5
                  Equity Interests..................................................................5
                  Event of Default..................................................................5
                  Excess Amount.....................................................................5
                  Exchange Act......................................................................5
                  Global Security...................................................................5

                                                  -i-

<PAGE>

                                                                                                 Page

                  Holder............................................................................5
                  Holder of Securities..............................................................5
                  Securityholder....................................................................5
                  Immediate Family Member...........................................................5
                  Indenture.........................................................................5
                  Issuer............................................................................6
                  Issuer Notice.....................................................................6
                  Issuer Order......................................................................6
                  Issuer Repurchase Notice..........................................................6
                  Issuer Repurchase Notice Date.....................................................6
                  Last Sale Price...................................................................6
                  NASDAQ............................................................................7
                  Officer...........................................................................7
                  Officers' Certificate.............................................................7
                  Opinion of Counsel................................................................7
                  Outstanding.......................................................................7
                  Paying Agent......................................................................8
                  Permitted Owner...................................................................8
                  Person............................................................................8
                  principal.........................................................................8
                  Principal Stockholders............................................................8
                  Redemption Date...................................................................8
                  Redemption Price..................................................................9
                  Registrar.........................................................................9
                  Registration Right Agreement......................................................9
                  Related Party.....................................................................9
                  Repurchase Date...................................................................9
                  Repurchase Price..................................................................9
                  Responsible Officer...............................................................9
                  Restricted Global Security........................................................9
                  Restricted Security..............................................................10
                  SEC..............................................................................10
                  Security ........................................................................10
                  Securities.......................................................................10
                  Securities Act...................................................................10
                  Subsidiary.......................................................................10
                  Surviving Person.................................................................10
                  TIA..............................................................................10
                  Trading Day......................................................................10
                  Trustee..........................................................................11

                                                  -ii-

<PAGE>

                                                                                                 Page

                  U.S. Government Obligations......................................................11

                                   ARTICLE TWO

                                   SECURITIES

         SECTION 2.1  Form and Dating..............................................................11
         SECTION 2.2  Execution and Authentication.................................................12
         SECTION 2.3  Registrar, Paying Agent and
                                    Conversion Agent...............................................14
         SECTION 2.4  Paying Agent to Hold Money in Trust..........................................15
         SECTION 2.5  Holder Lists  ...............................................................16
         SECTION 2.6  Transfer and Exchange........................................................16
         SECTION 2.7  Replacement Securities.......................................................17
         SECTION 2.8  Outstanding Securities.......................................................17
         SECTION 2.9  Temporary Securities.........................................................18
         SECTION 2.10  Cancellation................................................................18
         SECTION 2.11  Defaulted Interest..........................................................19
         SECTION 2.12  CUSIP Numbers...............................................................19
         SECTION 2.13  Global Securities...........................................................19
         SECTION 2.14  Transfer Restrictions.......................................................22

                                  ARTICLE THREE

                                    COVENANTS

         SECTION 3.1  Payment of Principal and Interest............................................23
         SECTION 3.2  Written Statement to Trustee.................................................23
         SECTION 3.3  Corporate Existence..........................................................23
         SECTION 3.4  Reports by the Issuer........................................................23
         SECTION 3.5  Waiver of Usury Defense......................................................25
         SECTION 3.6  Payment of Excess Cash Dividends.............................................25
         SECTION 3.7  Registration Rights..........................................................26

                                                  -iii-

<PAGE>

                                                                                                 Page

                                               ARTICLE FOUR

                                       REMEDIES OF THE TRUSTEE AND
                                   SECURITYHOLDERS ON EVENT OF DEFAULT

         SECTION 4.1  Event of Default Defined;
                                    Acceleration of Maturity; Waiver
                                    of Default.....................................................26
         SECTION 4.2  Collection of Indebtedness by
                                    Trustee; Trustee May Prove Debt................................29
         SECTION 4.3  Application of Proceeds......................................................32
         SECTION 4.4  Suits for Enforcement........................................................34
         SECTION 4.5  Restoration of Rights or Abandonment
                                    of Proceedings.................................................34
         SECTION 4.6  Limitations on Suits by
                                    Securityholders................................................34
         SECTION 4.7  Unconditional Right of
                                    Securityholders to Receive
                                    Principal, Premium and Interest, to
                                    Convert and to Institute Certain
                                    Suits..........................................................35
         SECTION 4.8  Powers and Remedies Cumulative; Delay
                                    or Omission Not Waiver of Default..............................36
         SECTION 4.9  Control by Securityholders...................................................36
         SECTION 4.10  Waiver of Past Defaults.....................................................37
         SECTION 4.11  Trustee to Give Notice of Default,
                                    But May Withhold in Certain
                                    Circumstances..................................................37
         SECTION 4.12  Right of Court to Require Filing of
                                    Undertaking to Pay Costs.......................................38
         SECTION 4.13  Waiver of Stay or Extension Laws............................................39

                                               ARTICLE FIVE

                                          CONCERNING THE TRUSTEE

         SECTION 5.1  Duties and Responsibilities of the
                                    Trustee; During Default; Prior to
                                    Default........................................................39

                                                  -iv-

<PAGE>

                                                                                                 Page

         SECTION 5.2  Certain Rights of the Trustee................................................41
         SECTION 5.3  Trustee Not Responsible for Recitals,
                                    Disposition of Securities or
                                    Application of Proceeds Thereof................................43
         SECTION 5.4  Trustee and Agents May Hold
                                    Securities; Collections, etc...................................43
         SECTION 5.5  Compensation and Indemnification of
                                    Trustee and Its Prior Claim....................................44
         SECTION 5.6  Right of Trustee to Rely on Officers'
                                    Certificate, etc...............................................45
         SECTION 5.7  Persons Eligible for Appointment as
                                    Trustee........................................................45
         SECTION 5.8  Resignation and Removal; Appointment
                                    of Successor Trustee...........................................46
         SECTION 5.9  Acceptance of Appointment by
                                    Successor Trustee..............................................48
         SECTION 5.10  Merger, Conversion, Consolidation or
                                    Succession to Business of Trustee..............................49

                                               ARTICLE SIX

                                      CONCERNING THE SECURITYHOLDERS

         SECTION 6.1  Evidence of Action Taken by
                                    Securityholders................................................50
         SECTION 6.2  Proof of Execution of Instruments and
                                    of Holding of Securities.......................................50
         SECTION 6.3  Holders to Be Treated as Owners..............................................50
         SECTION 6.4  Securities Owned by Issuer Deemed Not
                                    Outstanding....................................................51
         SECTION 6.5  Right of Revocation of Action Taken..........................................52
         SECTION 6.6  Record Date for Consents and Waivers.........................................52

                                              ARTICLE SEVEN

                                         SUPPLEMENTAL INDENTURES

         SECTION 7.1  Supplemental Indentures Without
                                    Consent of Securityholders.....................................53

                                                  -v-

<PAGE>

                                                                                                 Page

         SECTION 7.2  Supplemental Indentures with Consent
                                    of Securityholders.............................................55
         SECTION 7.3  Effect of Supplemental Indenture.............................................57
         SECTION 7.4  Documents to Be Given to Trustee.............................................57
         SECTION 7.5  Notation on Securities in Respect of
                                    Supplemental Indentures........................................57

                                              ARTICLE EIGHT

                                CONSOLIDATION, MERGER, SALE OR CONVEYANCE

         SECTION 8.1  Covenant Not to Merge, Consolidate,
                                    Sell or Convey Property Except
                                    Under Certain Conditions.......................................57
         SECTION 8.2  Successor Corporation or Entity
                                    Substituted....................................................58
         SECTION 8.3  Opinion of Counsel and Officers'
                                    Certificate to Trustee.........................................59

                                               ARTICLE NINE

                                        SATISFACTION AND DISCHARGE
                                      OF INDENTURE; UNCLAIMED MONEYS

         SECTION 9.1  Satisfaction and Discharge of
                                    Indenture......................................................60
         SECTION 9.2  Application by Trustee of Funds
                                    Deposited for Payment of
                                    Securities ....................................................61
         SECTION 9.3  Repayment of Moneys Held by Paying
                                    Agent..........................................................62
         SECTION 9.4  Return of Moneys Held by Trustee and
                                    Paying Agent Unclaimed for Two
                                    Years..........................................................62
         SECTION 9.5  Indemnity for U.S. Government
                                    Obligations....................................................63

                                                  -vi-

<PAGE>

                                                                                                 Page

                                               ARTICLE TEN

                                         MISCELLANEOUS PROVISIONS

         SECTION 10.1  Partners, Incorporators,
                                    Stockholders, Officers and
                                    Directors of Issue Exempt from
                                    Individual Liability...........................................63
         SECTION 10.2  Provisions of Indenture for the Sole
                                    Benefit of Parties and
                                    Securityholders................................................63
         SECTION 10.3  Successors and Assigns of Issuer
                                    Bound by Indenture.............................................63
         SECTION 10.4  Notices and Demands on Issuer,
                                    Trustee and Securityholders....................................64
         SECTION 10.5  Officers' Certificates and Opinions
                                    of Counsel; Statements to Be
                                    Contained Therein..............................................65
         SECTION 10.6  Payments Due on Saturdays, Sundays
                                    and Legal Holidays.............................................66
         SECTION 10.7  Conflict with TIA...........................................................67
         SECTION 10.8  Communications by Holders with Other
                                    Holders........................................................67
         SECTION 10.9  Issuer to Furnish Trustee Names and
                                    Addresses of Holders...........................................67
         SECTION 10.10  New York Law to Govern.....................................................67
         SECTION 10.11  Counterparts...............................................................68
         SECTION 10.12  Effect of Headings.........................................................68

                                              ARTICLE ELEVEN

                                         REDEMPTION OF SECURITIES

         SECTION 11.1  Right of Optional Redemption;
                                    Prices ........................................................68
         SECTION 11.2  Notice of Redemption; Partial
                                    Redemptions....................................................68
         SECTION 11.3  Payment of Securities Called for
                                    Redemption.....................................................70

                                                  -vii-

<PAGE>

                                                                                                 Page

         SECTION 11.4  Exclusion of Certain Securities from
                                    Eligibility for Selection for
                                    Redemption.....................................................71
         SECTION 11.5  Conversion Arrangement on Call for
                                    Redemption.....................................................72

                                              ARTICLE TWELVE

                                         CONVERSION OF SECURITIES

         SECTION 12.1  Conversion Privilege........................................................73
         SECTION 12.2  Exercise of Conversion Privilege............................................74
         SECTION 12.3  Fractional Shares...........................................................76
         SECTION 12.4  Adjustment of Conversion Price..............................................76
         SECTION 12.5  Continuation of Conversion Privilege
                                    in Case of Reclassification,
                                    Reorganization, Change, Merger,
                                    Consolidation or Sale of Assets................................81
         SECTION 12.6  Notice of Certain Events....................................................82
         SECTION 12.7  Taxes on Conversion.........................................................83
         SECTION 12.8  Issuer to Provide Class A Common
                                    Stock..........................................................84
         SECTION 12.9  Disclaimer of Responsibility for
                                    Certain Matters................................................85
         SECTION 12.10  Return of Funds Deposited for
                                    Redemption of Converted Securities.............................86

                                             ARTICLE THIRTEEN

                            RIGHT TO REQUIRE REDEMPTION UPON CHANGE IN CONTROL

         SECTION 13.1  Right to Require Redemption.................................................86
         SECTION 13.2  Notices; Method of Exercising
                                    Redemption Right, etc..........................................87
         SECTION 13.3  Definition of Change in Control.............................................89
         SECTION 13.4  Limitation on Right to Require
                                    Redemption.....................................................90

                                                  -viii-

<PAGE>

                                                                                                 Page

                                             ARTICLE FOURTEEN

                             REPURCHASE OF SECURITIES AT OPTION OF THE HOLDER

         SECTION 14.1  General      ...............................................................91
         SECTION 14.2  Issuer's Right to Elect Manner of
                                    Payment of Repurchase Price....................................93
         SECTION 14.3  Repurchase with Cash........................................................94
         SECTION 14.4  Payment by Issuance of Class A
                                    Common Stock...................................................94
         SECTION 14.5  Notice of Election..........................................................97
         SECTION 14.6  Covenants of the Issuer.....................................................99
         SECTION 14.7  Procedure upon Repurchase...................................................99
         SECTION 14.8  Taxes        ..............................................................100
         SECTION 14.9  Effect of Repurchase Notice................................................100
         SECTION 14.10  Deposit of Repurchase Price...............................................102
         SECTION 14.11  Securities Repurchased in Part............................................102
         SECTION 14.12  Issuer to Comply with Securities
                                    Laws upon Purchase of Securities..............................103
         SECTION 14.13  Repayment to the Issuer...................................................103

SIGNATURES........................................................................................104

EXHIBIT A -- FORM OF SECURITY
</TABLE>

                                      -ix-

<PAGE>

                  THIS INDENTURE, dated as of February 15, 2000 between American
Tower Corporation,  a Delaware  corporation (the "Issuer"),  and The Bank of New
York, a New York banking
corporation (the "Trustee"),

                              W I T N E S S E T H :

                  WHEREAS,  the Issuer has duly authorized the issue of its 5.0%
Convertible  Notes Due 2010 (the  "Securities") of  substantially  the tenor and
amount hereinafter set forth;

                  WHEREAS,  the Issuer has duly  authorized  the  execution  and
delivery  of  this   Indenture  to  provide,   among  other   things,   for  the
authentication, delivery and administration of the Securities; and

                  WHEREAS,  all things  necessary to make this Indenture a valid
indenture and agreement according to its terms have been done;

                  NOW, THEREFORE:

                  In  consideration  of the  premises  and the  purchases of the
Securities by the Holders thereof,  the Issuer and the Trustee mutually covenant
and agree for the equal and proportionate benefit of the respective Holders from
time to time of the Securities as follows:

                                   ARTICLE ONE

                                   DEFINITIONS

                  SECTION 1.1 Certain Terms Defined. The following terms (except
as  otherwise  expressly  provided  or  unless  the  context  otherwise  clearly
requires) for all purposes of this  Indenture and of any indenture  supplemental
hereto shall have the respective  meanings specified in this Section.  All other
terms used in this Indenture which are defined in the TIA, or the definitions of
which  in the  Securities  Act are  referred  to in the TIA  (except  as  herein
otherwise expressly provided or unless the context otherwise requires), shall

<PAGE>

have the meaning  assigned to such terms in the TIA and the Securities Act as in
force at the date of this  Indenture.  All accounting  terms used herein and not
expressly  defined  shall have the  meanings  given to them in  accordance  with
generally  accepted  accounting  principles,  and the term  "generally  accepted
accounting principles" shall mean such accounting principles which are generally
accepted at the date or time of any  computation.  The words "herein",  "hereof"
and  "hereunder"  and other words of similar import refer to this Indenture as a
whole and not to any particular Article, Section or other subdivision. The terms
defined in this Article include the plural as well as the singular.

                  "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 the purposes of this definition,
"control"  when used with  respect to any  specified  Person  means the power to
direct the  management  and  policies of such  Person,  directly or  indirectly,
whether  through the ownership of voting  securities,  by contract or otherwise;
and the terms  "controlling" and "controlled"  have meanings  correlative to the
foregoing.

                  "Agent" means any Registrar, Paying Agent or Conversion Agent.

                  "Board of  Directors"  means  either the Board of Directors of
the Issuer or any committee of such Board duly authorized to act on its behalf.

                  "Board  Resolution"  means a copy of one or more  resolutions,
certified by the secretary or an assistant  secretary of the Issuer to have been
duly adopted by the Board of Directors and to be in full force and effect on the
date of such certification, and delivered to the Trustee.

                  "Business  Day" means a day which in the City and State of New
York is neither  Saturday,  Sunday,  a legal  holiday nor a day on which banking
institutions  and  trust  companies  are  authorized  by  law or  regulation  or
executive order to close.

                                       -2-

<PAGE>

                  "Capital  Stock"  means  (i) in  the  case  of a  corporation,
capital stock,  (ii) in the case of any association or business entity,  any and
all shares,  interests,  participations,  rights or other  equivalents  (however
designated) or capital stock and (iii) in the case of a partnership, partnership
interests  (whether  general or limited) and 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, such partnership.

                  "Cash  Equivalents"  means (i)  United  States  dollars,  (ii)
securities  issued or  directly  and fully  guaranteed  or insured by the United
States government or any agency or instrumentality  thereof having maturities of
less than one year from the date of acquisition,  (iii)  certificates of deposit
and eurodollar time deposits with maturities of less than one year from the date
of acquisition,  bankers'  acceptances with maturities of less than one year and
overnight  bank  deposits,  in each case  with any  lender  party to the  Credit
Agreements or with any domestic  commercial  bank having  capital and surplus in
excess of  $500,000,000  and a Keefe  Bank Watch  Rating of "B" or better,  (iv)
repurchase  obligations  with a term of not more than seven days for  underlying
securities  of the types  described in clauses (ii) and (iii)  entered into with
any financial  institution meeting the qualifications  specified in clause (iii)
above and (v) commercial paper having the highest rating obtainable from Moody's
Investors Service, Inc. or Standard & Poor's Ratings Services, a division of the
McGraw-Hill Companies,  Inc., and in each case maturing within nine months after
the date of acquisition.

                  "Change in Control" has the meaning  assigned to it in Section
13.3.

                  "Change in Control  Repurchase  Date" has the meaning assigned
to it in Section 13.1.

                  "Change in Control  Repurchase Price" has the meaning assigned
to it in Section 13.1.

                                       -3-

<PAGE>

                  "Class A Common  Stock"  means the Class A Common  Stock,  par
value $0.01 per share,  of the Issuer as the same exists at the Closing  Date or
as such stock may be reconstituted from time to time.

                  "Closing  Date"  means  the date (or,  if more  than one,  the
earliest date) of original issuance of the Securities.

                  "Common  Stock"  means the Class A Common  Stock,  the Class B
Common Stock,  par value $0.01 per share and the Class C Common Stock, par value
$0.01 per share, of the Issuer as the same exists at the Closing Date or as such
stock may be reconstituted from time to time.

                  "Conversion  Agent" has the meaning  assigned to it in Section
2.3.

                  "Conversion   Price"  means  the   principal   amount  of  the
Securities  convertible  into one  share of Class A  Common  Stock,  subject  to
adjustment in accordance with Section 12.4.

                  "Corporate  Trust  Office"  means the office of the Trustee at
which the corporate trust business of the Trustee shall, at any particular time,
be  principally  administered,  which  office  is, at the date as of which  this
Indenture is dated, located at 101 Barclay Street, 21W, New York, NY 10286.

                  "Date of Conversion" has the meaning assigned to it in Section
12.2.

                  "Depositary"  means  with  respect to  Securities,  a clearing
agency that is  registered  as such under the Exchange Act and is  designated by
the Issuer to act as Depositary for such Securities (or any successor securities
clearing agency so registered.)

                  "Disposition" has the meaning assigned to it in Section 8.1.

                                       -4-

<PAGE>

                  "DTC"  means  The  Depository   Trust  Company,   a  New  York
corporation.

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

                  "Event of Default"  means any event or condition  specified as
such in Section 4.1.

                  "Excess Amount" has the meaning assigned to it in Section 3.6.

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

                  "Global  Security"  means a Security that is registered in the
security register kept by the Registrar in the name of a Depositary or a nominee
thereof.

                  "Holder",  "Holder of Securities",  "Securityholder"  or other
similar  terms mean in the case of any  Security,  the Person in whose name such
Security is registered  in the security  register kept by the Registrar for that
purpose in accordance with the terms hereof.

                  "Immediate   Family  Member"   means,   with  respect  to  any
individual, such individual's spouse (past or current),  descendants (natural or
adoptive,  of the whole or half blood) of the parents of such  individual,  such
individual's   grandparents   and  parents   (natural  or  adoptive),   and  the
grandparents,  parents and descendants of parents  (natural or adoptive,  of the
whole or half blood) of such individual's spouse (past or current).

                  "Indenture"  means this instrument as originally  executed and
delivered or, if amended or  supplemented as herein  provided,  as so amended or
supplemented.

                                       -5-

<PAGE>

                  "Issuer"  means  American   Tower   Corporation,   a  Delaware
corporation, and, subject to Article Eight, its successors and assigns.

                  "Issuer  Notice"  has the  meaning  assigned  to it in Section
13.2.

                  "Issuer Order" means a written statement,  request or order of
the  Issuer  which  is  signed  in its  name by its  Chairman  of the  Board  of
Directors,  its  Chief  Executive  Officer,  its  President,  a Chief  Operating
Officer,  a Vice  President,  or  its  Chief  Financial  Officer,  and,  without
duplication,  by its Treasurer,  an Assistant  Treasurer,  its  Controller,  its
Secretary  or an  Assistant  Secretary,  of the  Issuer,  and  delivered  to the
Trustee.

                  "Issuer  Repurchase  Notice" has the meaning assigned to it in
Section 14.5.

                  "Issuer Repurchase Notice Date" has the meaning assigned to it
in Section 14.3.

                  "Last Sale  Price" on any day means the last sale price of the
Class A Common  Stock  as  reported  on the  composite  tape for New York  Stock
Exchange  listed  stocks  (or if not  listed  or  admitted  to  trading  on such
exchange,  then on the principal national securities exchange on which the Class
A Common  Stock is listed or admitted to trading,  or, if not listed or admitted
to  trading  on  any  national  securities  exchange,  on  NASDAQ  or a  similar
organization if NASDAQ is no longer reporting information) on such day or, if no
such sale takes place on such day, the last sale price for such day shall be the
average of the  closing bid and asked  prices  regular way on the New York Stock
Exchange (or, if not listed or admitted to trading on such exchange, then on the
principal  national  securities  exchange  on which the Class A Common  Stock is
listed or admitted  to trading,  or, if not listed or admitted to trading on any
national securities  exchange,  on NASDAQ or a similar organization if NASDAQ is
no longer reporting information) on such day.

                                       -6-

<PAGE>

                  "NASDAQ" means the National  Association of Securities Dealers
Automated Quotations National Market System.

                  "Officer"  means the Chairman of the Board of  Directors,  the
Chief  Executive  Officer,  the President,  a Chief  Operating  Officer,  a Vice
President,  the Chief Financial Officer, the Treasurer,  an Assistant Treasurer,
the Controller, the Secretary or an Assistant Secretary, of the Issuer.

                  "Officers'  Certificate"  means a  certificate  signed  by the
Chairman of the Board of Directors,  the Chief Executive Officer, the President,
a Chief Operating Officer, a Vice President, or the Chief Financial Officer and,
without duplication,  by the Treasurer, an Assistant Treasurer,  Controller, the
Secretary  or an  Assistant  Secretary,  of the  Issuer,  and  delivered  to the
Trustee.  Each such  certificate  shall include the  statements  provided for in
Section 10.5, if and to the extent required hereby.

                  "Opinion  of  Counsel"  means a written  opinion,  in form and
substance reasonably satisfactory to the Trustee, of counsel, who may be counsel
to the Issuer and who shall be  acceptable  to the  Trustee.  Each such  opinion
shall include the statements  provided for in Section 10.5, if and to the extent
required hereby.

                  "Outstanding",  when used with reference to Securities, shall,
subject to the provision of Section 6.4,  mean, as of any  particular  time, all
Securities  authenticated  and  delivered by the Trustee  under this  Indenture,
except

                  (a)  Securities theretofore cancelled by the
         Trustee or delivered to the Trustee for cancellation;

                  (b)  Securities,  or  portions  thereof,  for the  payment  or
         redemption  of which  moneys in the  necessary  amount  shall have been
         deposited  in trust with the  Trustee or with any Paying  Agent  (other
         than the Issuer) or shall have been set aside, segregated and

                                       -7-

<PAGE>

         held in trust by the Issuer (if the Issuer  shall act as its own Paying
         Agent),  provided that if such  Securities  are to be redeemed prior to
         the maturity  thereof,  notice of such redemption shall have been given
         as herein provided, or provision satisfactory to the Trustee shall have
         been made for giving such notice; and

                  (c)  Securities  in  substitution  for which other  Securities
         shall have been  authenticated and delivered,  or which shall have been
         paid,  pursuant to the terms of Section 2.7 (unless proof  satisfactory
         to the Trustee is presented  that any of such  Securities  is held by a
         Person in whose  hands  such  Security  is a legal,  valid and  binding
         obligation  of the Issuer),  Securities  converted  into Class A Common
         Stock pursuant hereto and Securities not deemed Outstanding pursuant to
         and for the purposes of the last sentence of Section 11.2.

                  "Paying Agent" has the meaning assigned to it in Section 2.3.

                  "Permitted  Owner" has the  meaning  assigned to it in Section
13.3.

                  "Person"  means  any  individual,  corporation,   partnership,
limited  liability  company,  joint venture,  association,  joint stock company,
trust,  unincorporated  organization  or  government  or any agency or political
subdivision thereof.

                  "principal"  wherever used with reference to the Securities or
any Security or any portion thereof shall be deemed to include "and premium,  if
any" whether or not so specified.  (Reference  is also made to Sections  13.2(c)
and 14.9.)

                  "Principal  Stockholders"  has the  meaning  assigned to it in
Section 13.3.

                  "Redemption  Date",  has the meaning assigned to it in Section
11.2.

                                       -8-

<PAGE>

                  "Redemption  Price", when used with respect to any Security to
be  redeemed,  means the price at which it is to be  redeemed  pursuant  to this
Indenture.

                  "Registrar" has the meaning assigned to it in Section 2.3.

                  "Registration  Right Agreement" means the Registration  Rights
Agreement,  dated as of  February  15,  2000,  among the Issuer and the  initial
purchasers named therein.

                  "Related  Party" with respect to any individual  means (i) any
Immediate   Family  Member  of  such   individual   or  (ii)  any  Person,   the
beneficiaries, stockholders, partners, owners or Persons beneficially holding an
80% or more  controlling  interest  of which  consist of such  individual  or an
Immediate Family Member.

                  "Repurchase  Date" has the  meaning  assigned to it in Section
14.1.

                  "Repurchase  Price" has the meaning  assigned to it in Section
14.1.

                  "Responsible  Officer",  when used with respect to the Trustee
means  any  officer  within  the  corporate  trust  department  of the  Trustee,
including any vice  president,  assistant vice president,  assistant  secretary,
assistant  treasurer,  trust  officer  or  any  other  officer  of  the  Trustee
customarily  performing  corporate trust functions similar to those performed by
the Persons who at the time shall be such officers, respectively, or to whom any
corporate  trust matter is referred  because of such  Person's  knowledge of and
familiarity with the particular subject and who shall have direct responsibility
for the administration of this Indenture.

                  "Restricted Global Security" has the meaning assigned to it in
Section 2.1.

                                       -9-

<PAGE>

                  "Restricted  Security"  means any Security  issued in exchange
for an  interest  in the  Restricted  Global  Security  until  such  time as the
Restricted  Security legend contemplated in Section 2.14 need not be provided on
the Security.

                  "SEC" means the  Securities  and  Exchange  Commission  or any
successor agency.

                  "Security" or "Securities" has the meaning stated in the first
recital  of  this   Indenture  and  more   particularly   means  any  securities
authenticated and delivered under this Indenture.

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

                  "Subsidiary"   means,   with   respect  to  any  Person,   any
corporation,  association or other business entity of which more than 50% of the
total  voting  power  of  Equity  Interests  entitled  (without  regard  to  the
occurrence of any contingency) to vote in the election of directors, managers or
trustees or other  governing  body thereof is at the time owned or controlled by
such Person  (regardless of whether such Equity  Interests are owned directly or
through one or more other Subsidiaries of such Person or a combination thereof).

                  "Surviving  Person" means, with respect to any Person involved
in or that  makes  any  Disposition,  the  Person  formed by or  surviving  such
Disposition or the Person to which such Disposition is made.

                  "TIA"  (except as otherwise  provided in Sections 7.1 and 7.2)
means the Trust  Indenture  Act of 1939 as in force at the date as of which this
Indenture was originally issued.

                  "Trading Day" means each Monday, Tuesday, Wednesday,  Thursday
and  Friday,  other  than  any day on which  securities  are not  traded  on the
applicable securities exchange or in the applicable securities market.

                                      -10-

<PAGE>

                  "Trustee"  means the entity  identified  as  "Trustee"  in the
first  paragraph  hereof and,  subject to the provisions of Article Five,  shall
also include any successor  trustee.  "Trustee"  shall also mean or include each
Person  who is then a trustee  hereunder  if at any time  there is more than one
such Person.

                  "U.S. Government  Obligations" means direct obligations of the
United States of America, backed by its full faith and credit.

                                   ARTICLE TWO

                                   SECURITIES

                  SECTION 2.1 Form and Dating.  The Securities and the Trustee's
certificate of  authentication  shall be  substantially in the form of Exhibit A
(including the legends appearing  thereon),  the terms of which are incorporated
in and made a part of this Indenture. The Securities may have notations, legends
or endorsements  required by law,  securities exchange (including NASDAQ) rules,
agreements  to which the Issuer is subject or usage,  including,  if required by
Section 2.13, the legend contemplated thereby. The Issuer shall approve the form
of the Securities and any notation, legend or endorsement on them. Each Security
shall be dated the date of its authentication.

                  Upon their original  issuance,  Securities  shall be issued in
the form of one or more Global Securities  without interest coupons and shall be
registered in the name of DTC, as Depositary,  or its nominee and deposited with
the Trustee,  as custodian for DTC, for credit by DTC to the respective accounts
of  beneficial  owners of the  Securities  represented  thereby  (or such  other
accounts  as  they  may  direct).   Such  Global   Security  or  Securities  are
collectively  herein called the  "Restricted  Global  Security".  The Restricted
Global  Security and any  Restricted  Security  shall bear a different  CUSIP or
other  identifying  number from any  Security  that is not a  Restricted  Global
Security or Restricted Security.

                                      -11-

<PAGE>

                  SECTION 2.2 Execution and  Authentication.  Two Officers shall
sign the  Securities  for the  Issuer  by  manual or  facsimile  signature.  The
Issuer's seal shall be reproduced on the Securities.

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

                  A security shall not be valid until the Trustee manually signs
the certificate of authentication on the Security.  The signature of the Trustee
shall be conclusive evidence that the Security has been authenticated under this
Indenture.

                  The Trustee shall  authenticate  Securities for original issue
in the  aggregate  principal  amount  of  $400,000,000  upon  an  Issuer  Order;
provided,  however,  that if the Issuer  sells any  Securities  pursuant  to the
option in the Purchase Agreement, dated February 9, 2000, between the Issuer and
the  initial  purchasers  named  therein,  then the Trustee  shall  authenticate
Securities  for  original  issue  in the  aggregate  principal  amount  of up to
$450,000,000  upon an Issuer Order. The Issuer Order shall specify the amount of
Securities  to be  authenticated  and the date on which  the  original  issue of
Securities is to be authenticated.  The aggregate principal amount of Securities
outstanding  at any time may not exceed  the  amount  set forth in the  previous
sentence except as provided in Section 2.7.

                  The Trustee's  authentication  of  Securities  pursuant to the
next  preceding  paragraph  shall be  conditioned  upon  receipt  of each of the
following in form and  substance  reasonably  satisfactory  to the Trustee on or
prior to the Closing Date:

                  A.  An Officer's Certificate to the effect that:

                           (1)  All conditions required to be satisfied
                  under this Indenture for the issuance of the

                                      -12-

<PAGE>

                  Securities  have been so  satisfied on or prior to the Closing
                  Date; and

                           (2) No Event of Default  shall have  occurred  and be
                  continuing.

                  B. An Opinion of Counsel to the effect that:

                           (1) The execution and delivery of the Indenture,  the
                  issuance of the  Securities  and the  fulfillment of the terms
                  herein and therein  contemplated  will not  conflict  with the
                  charter or bylaws of the Issuer,  or constitute a breach of or
                  default under any material agreement,  indenture,  evidence of
                  indebtedness,  mortgage,  deed  of  trust  or  other  material
                  agreement  or  instrument  known to such  counsel to which the
                  Issuer  is a  party  or by  which  it is  bound,  or any  law,
                  administrative  regulation,  rule,  judgment,  order or decree
                  known to such counsel to be applicable to the Issuer or any of
                  its properties;

                           (2) The  Indenture  has been duly  authorized  by the
                  Issuer,  executed and delivered by the Issuer, and is a legal,
                  valid and  binding  agreement  of the  Issuer  enforceable  in
                  accordance with its terms,  except as such  enforceability may
                  be  limited   by   bankruptcy,   insolvency,   reorganization,
                  receivership, moratorium and similar laws affecting the rights
                  and remedies of creditors and obligations of debtors generally
                  and by the effect of  general  principles  of equity,  whether
                  applied by a court of law or equity;

                           (3) All legally required proceedings by the Issuer in
                  connection  with  the   authorization  and  issuances  of  the
                  Securities have been duly taken,  and all orders,  consents or
                  other  authorizations or approvals of any public board or body
                  legally  required for the validity of the Securities have been
                  obtained; and

                                      -13-

<PAGE>

                           (4) The Securities,  when executed and  authenticated
                  in accordance  with the terms of this  Indenture and delivered
                  upon  payment  therefor,  will be  legal,  valid  and  binding
                  obligations of the Issuer enforceable in accordance with their
                  terms,  except  as  such  enforceability  may  be  limited  by
                  bankruptcy,    insolvency,    reorganization,    receivership,
                  moratorium  and similar laws affecting the rights and remedies
                  of creditors and  obligations of debtors  generally and by the
                  effect of general  principles of equity,  whether applied by a
                  court of law or equity.

                  The Trustee may appoint an authenticating  agent acceptable to
the  Issuer  to  authenticate  Securities.  Unless  limited  by the term of such
appointment,  an authenticating  agent may authenticate  Securities 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 the Issuer or an Affiliate of the Issuer.

                  The  Securities  shall be  issuable  only in  registered  form
without coupons and only in  denominations  of $1,000 and any integral  multiple
thereof.

                  SECTION 2.3 Registrar,  Paying Agent and Conversion Agent. The
Issuer shall  maintain in The Borough of Manhattan in The City of New York,  New
York, an office or agency where  Securities may be presented for registration of
transfer or for exchange ("Registrar"), an office or agency where Securities may
presented for payment and repurchase ("Paying Agent"), an office or agency where
Securities may be presented for conversion ("Conversion Agent") and an office or
agency  where  notices  and  demands  to or upon the  Issuer in  respect  of the
Securities and this Indenture may be served. The Registrar shall keep a register
of the Securities and of their transfer and exchange. The Issuer may appoint one
or more  co-Registrars,  one or more  additional  Paying  Agents and one or more
additional  Conversion  Agents,  which may be inside or outside  The  Borough of
Manhattan. The term "Registrar" includes any co-

                                      -14-
<PAGE>

Registrar,  the term "Paying Agent" includes any additional Paying Agent and the
term "Conversion Agent" includes any additional Conversion Agent. The Issuer may
change any  Registrar,  Paying Agent or Conversion  Agent without  notice to any
Holder.  If the Issuer fails to appoint or maintain another person as Registrar,
Paying Agent or Conversion  Agent,  the Trustee shall act as such. The Issuer or
any Affiliate of the Issuer may act as Registrar or Conversion Agent. Except for
purposes of Article  Nine,  the Issuer or any Affiliate of the Issuer may act as
Paying Agent.

                  The Issuer shall enter into an  appropriate  agency  agreement
with any Agent not a party to this Indenture.  The agreement shall implement the
provisions  of this  Indenture  that  relate to such  Agent.  The  Issuer  shall
promptly  notify the Trustee of the name and address of any Agent not a party to
this  Indenture.  If the Issuer  fails to maintain a  Registrar,  Paying  Agent,
Conversion  Agent or agent for service of notices and demands,  or fails to give
the foregoing notice, the Trustee shall act as such.

                  The Issuer initially appoints the Trustee as Registrar, Paying
Agent, Conversion Agent and agent for service of notices and demands.

                  SECTION  2.4 Paying  Agent to Hold  Money in Trust.  Not later
than 11:00 a.m.,  Eastern Standard Time, on each due date of the principal of or
interest on any Securities, the Issuer shall deposit with the Paying Agent a sum
of money in  immediately  available  funds  sufficient to pay such  principal or
interest so becoming due. Subject to Section 9.2, the Paying Agent shall hold in
trust for the  benefit of  Securityholders  or the Trustee all money held by the
Paying Agent for the payment of principal of or interest on the Securities,  and
shall  notify the  Trustee in writing of any default by the Issuer in making any
such payment.  If the Issuer or an Affiliate of the Issuer acts as Paying Agent,
it shall on or  before  each due date of the  principal  of or  interest  on any
Securities  segregate the money and hold it as a separate trust fund. The Issuer
at any  time may  require  a Paying  Agent  to pay all  money  held by it to the
Trustee,  and the Trustee may at any time during the

                                      -15-
<PAGE>

continuance of any default, upon written request to a Paying Agent, require such
Paying Agent to  forthwith  pay to the Trustee all sums so held in trust by such
Paying Agent. Upon doing so, the Paying Agent (other than the Issuer) shall have
no further liability for the money.

                  SECTION 2.5 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 the Holders.  If the Trustee is not the Registrar,
the Issuer  shall  promptly  furnish to the Trustee on or before  each  interest
payment  date 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 for
the names and addresses of the Holders.

                  SECTION  2.6  Transfer  and  Exchange.   When  a  Security  is
presented to the Registrar  with a request to register a transfer  thereof,  the
Registrar  shall  register the transfer as requested,  and, when  Securities are
presented  to the  Registrar  with a  request  to  exchange  them  for an  equal
principal amount of Securities of other authorized denominations,  the Registrar
shall make the exchange as requested;  provided that every Security presented or
surrendered  for  registration of transfer or exchange shall be duly endorsed or
be accompanied by a written  instrument of transfer in form  satisfactory to the
Issuer and the  Registrar  duly  executed by the Holder  thereof or his attorney
duly authorized in writing.  To permit  registration of transfers and exchanges,
the Issuer shall  execute and the Trustee shall  authenticate  Securities at the
Issuer's  request.  The Issuer shall not be required (i) to issue,  register the
transfer of or exchange  Securities  during a period beginning at the opening of
business on a Business Day 15 days before the day of any selection of Securities
for redemption under Section 11.2 and ending at the close of business on the day
of  selection,  or (ii) to register  the transfer of or exchange any Security so
selected for redemption in whole or in part,  except the  unredeemed  portion of
any Security  being  redeemed in part. Any exchange or transfer shall be without
charge,  except that the Issuer may require payment of a sum sufficient to

                                      -16-
<PAGE>

cover any tax or other  governmental  charge  that may be  imposed  in  relation
thereto,  but this provision shall not apply to any exchange pursuant to Section
7.5 or 11.2.  Prior to due  presentment  for  registration  of  transfer  of any
Security, the Trustee, any Agent and the Issuer may deem and treat the Person in
whose name any Security is registered as the absolute owner of such Security for
the purpose of receiving  payment of principal of and interest on such  Security
and for all other purposes whatsoever,  whether or not such Security is overdue,
and none of the Trustee,  any Agent or the Issuer shall be affected by notice to
the contrary.

                  SECTION 2.7 Replacement Securities. If a mutilated Security is
surrendered  to the  Trustee,  or if the  Holder of a Security  claims  that the
Security has been lost,  destroyed or wrongfully  taken,  and neither the Issuer
nor the Trustee has received written notice that such Security has been acquired
by a bona  fide  purchaser,  the  Issuer  shall  issue  and  the  Trustee  shall
authenticate a replacement  Security if the requirements of Section 8-405 of the
New York Uniform  Commercial  Code, as in effect on the date of this  Indenture,
are met,  and there  shall have been  delivered  to the  Issuer and the  Trustee
evidence to their satisfaction of the loss, destruction or theft of any Security
if such is the case.  An indemnity  bond will be required  that is sufficient in
the judgment of the Issuer and the Trustee to protect the Issuer, the Trustee or
any Agent from any loss which any of them may suffer if a Security is  replaced.
The  Issuer may charge  the  Holder  for its  expenses  (including  the fees and
expenses of the Trustee) in replacing a Security.  Every replacement Security is
an additional  obligation of the Issuer.  The provisions of this Section 2.7 are
exclusive  and shall  preclude all other rights and remedies with respect to the
replacement or payment of mutilated, destroyed, lost or stolen Securities.

                  SECTION 2.8 Outstanding Securities. The Securities Outstanding
at any time are all of the Securities  authenticated by the Trustee,  except for
those canceled by it, those delivered to it for cancellation and those described
in this Section 2.8 as not Outstanding.

                                      -17-

<PAGE>

                  If a Security is replaced  pursuant to Section  2.7, it ceases
to be Outstanding  until a Responsible  Officer of the Trustee actually receives
proof  satisfactory  to it that the  replaced  Security  is held by a bona  fide
purchaser.

                  If the Paying  Agent (other than the Issuer or an Affiliate of
the Issuer) holds on a redemption date or maturity date money  sufficient to pay
the principal of and accrued  interest on Securities  payable on that date, then
on and after that date such  Securities  cease to be Outstanding and interest on
them ceases to accrue.

                  Subject  to  Section  6.4,  a  Security  does not  cease to be
Outstanding because the Issuer or an Affiliate of the Issuer holds the Security.

                  SECTION 2.9 Temporary Securities.  Until definitive Securities
are ready for  delivery,  the  Issuer  may  prepare  and,  upon the order of the
Issuer,  the  Trustee  shall  authenticate   temporary   Securities.   Temporary
Securities shall be  substantially in the form of definitive  Securities but may
have variations that the Issuer considers  appropriate for temporary Securities.
Without  unreasonable  delay,  the Issuer  shall  prepare and the Trustee  shall
authenticate  definitive Securities in exchange for temporary Securities.  Until
such  exchange,  temporary  Securities  shall be  entitled  to the same  rights,
benefits and privileges as definitive Securities.

                  SECTION 2.10 Cancellation.  The Issuer at any time may deliver
Securities  to the Trustee for  cancellation.  The  Registrar,  Paying Agent and
Conversion Agent shall forward to the Trustee any Securities surrendered to them
for transfer, exchange, payment or conversion. The Trustee and no one else shall
cancel all Securities surrendered for transfer, exchange, payment, conversion or
cancellation.  The Issuer may not issue new Securities to replace  Securities it
has paid or  delivered  to the  Trustee  for  cancellation  or which  have  been
converted.  All  canceled  Securities  shall be held by the Trustee and shall be
disposed of in accordance with its customary procedures (and

                                      -18-

<PAGE>

certification of their cancellation shall be delivered to the Issuer).

                  SECTION 2.11 Defaulted  Interest.  If the Issuer defaults in a
payment of interest on the  Securities,  it shall pay the defaulted  interest in
any lawful manner plus, to the extent lawful,  interest payable on the defaulted
interest,  to the persons who are Holders on a subsequent  special  record date,
which date shall be at least five  Business  Days prior to the payment  date, in
each case at the rate provided in the  Securities and in Section 3.1. The Issuer
shall fix or cause to be fixed each such special  record date and payment  date.
At least 15 days before a special record date, the Issuer (or the Trustee in the
name of and at the expense of the Issuer)  shall forward to the Holders a notice
prepared by the Issuer that states the special record date, the related  payment
date and the amount of such interest to be paid.

                  SECTION  2.12  CUSIP  Numbers.   The  Issuer  in  issuing  the
Securities may use "CUSIP"  numbers (if then generally in use),  and, if so, the
Trustee shall use "CUSIP"  numbers in notices of redemption as a convenience  to
Holders;  provided that any such notice may state that no representation is made
as to the  correctness of such numbers either as printed on the Securities or as
contained in any notice of  redemption  and that  reliance may be placed only on
the  other  identification  numbers  printed  on the  Securities,  and any  such
redemption  shall not be affected by any defect in or omission of such  numbers.
The  Company  will  promptly  notify the  Trustee  of any change in the  "CUSIP"
numbers.

                  SECTION 2.13 Global Securities.

                  (a) Each Global  Security  authenticated  under this Indenture
shall be registered in the name of the  Depositary  designated by the Issuer for
such Global  Security or a nominee thereof and delivered to such Depositary or a
nominee  thereof or  custodian  therefor,  and each such Global  Security  shall
constitute a single Security for all purposes of this Indenture.

                                      -19-

<PAGE>

                  (b) Notwithstanding any other provision in this Indenture,  no
Global Security may be exchanged in whole or in part for Securities  registered,
and no transfer of a Global  Security in whole or in part may be registered,  in
the name of any Person other than the Depositary  for such Global  Security or a
nominee  thereof unless (i) such  Depositary (A) has notified the Issuer and the
Trustee in writing that it is unwilling or unable to continue as Depositary  for
such Global  Security or (B) has ceased to be a clearing  agency  registered  as
such under the  Exchange Act or  announces  an  intention  permanently  to cease
business or does in fact do so, (ii) there shall have occurred and be continuing
an Event of Default  with respect to such Global  Security,  or (iii) the Issuer
delivers an  Officers'  Certificate  to the Trustee  stating that the Issuer has
determined not to have all the Securities represented by the Global Security.

                  (c)  If any  Global  Security  is to be  exchanged  for  other
Securities or cancelled in whole, it shall be surrendered by or on behalf of the
Depositary  or its  nominee  to the  Trustee,  as  Registrar,  for  exchange  or
cancellation,  as  provided  in this  Article.  If any Global  Security is to be
exchanged for other  Securities or cancelled in part, or if another  Security is
to be  exchanged  in whole or in part for a  beneficial  interest  in any Global
Security,  in each case as provided in this Article, then either (i) such Global
Security shall be so surrendered  for exchange or  cancellation,  as provided in
this Article, or (ii) the principal amount thereof shall be reduced or increased
by an amount equal to the portion  thereof to be so exchanged or  cancelled,  or
equal to the  principal  amount of such other  Security to be so exchanged for a
beneficial  interest  therein,  as the case may be,  by means of an  appropriate
adjustment  made on the records of the  Trustee,  as  Registrar,  whereupon  the
Trustee shall instruct the Depositary or its authorized representative to make a
corresponding  adjustment  to its  records  in  accordance  with its  rules  and
procedures.  Upon any such  surrender or  adjustment of a Global  Security,  the
Trustee shall as provided in this Article,  authenticate  and make available for
delivery any  Securities  issuable in exchange for such Global  Security (or any
portion thereof)

                                      -20-

<PAGE>

to or upon the order of,  and  registered  in such names as may be  directed  in
writing by, the Depositary or its authorized representative. Upon the request of
the Trustee in connection with the occurrence of any of the events  specified in
the preceding paragraph, the Issuer shall promptly make available to the Trustee
a reasonable supply of Securities that are not in the form of Global Securities.
The Trustee  shall be entitled to rely upon any order,  direction  or request of
the Depositary or its authorized  representative which is given or made pursuant
to this  Article  if such  order,  direction  or  request  is  given  or made in
accordance with the Depositary's rules and procedures.

                  (d)  Every   Security   authenticated   and   delivered   upon
registration of transfer of, or in exchange for or in lieu of, a Global Security
or any portion thereof, whether pursuant to this Article or otherwise,  shall be
authenticated  and  delivered in the form of, and shall be, a registered  Global
Security,  unless such Security is registered in the name of a Person other than
the Depositary for such Global Security or a nominee thereof, in which case such
Registered  Security shall be authenticated  and delivered in definitive,  fully
registered form, without interest coupons.

                  (e) The  Depositary or its nominee,  as registered  owner of a
Global  Security,  shall be the Holder of such Global  Security for all purposes
under the Indenture and the Securities,  and owners of beneficial interests in a
Global Security shall hold such interests pursuant to the Depositary's rules and
procedures.  Accordingly,  any  such  owner's  beneficial  interest  in a Global
Security  will be shown  only on, and the  transfer  of such  interest  shall be
effected only through,  records  maintained by the  Depositary or its nominee or
its  participants  and such owners of beneficial  interests in a Global Security
will not be  considered  the owners or  holders  thereof.  Notices  given to the
Holders of the  Security  shall be deemed given if sent to the  Depositary.  The
Trustee shall have no obligation to the beneficial owners of the Securities.

                                      -21-

<PAGE>

                  (f) Upon the transfer of beneficial  interests in a Restricted
Global  Security  under  circumstances  permitting the removal of the Restricted
Securities legend contemplated in Section 2.14 if the Securities  represented by
such  beneficial  interest  were  not in the  form of a  Global  Security,  such
transferred beneficial interest shall be represented by a beneficial interest in
a Global Security that is not a Restricted Global Security.

                  SECTION 2.14 Transfer  Restrictions.  (a) Securities  shall be
stamped or  otherwise  be  imprinted  with the legends  containing  the transfer
restrictions  set forth on the face of the text of the  Securities  attached  as
Exhibit  A  hereto.  The  legends  so  provided  on the  face of the text of the
Securities that relate to Restricted Securities and Restricted Global Securities
may be removed  from such  Security,  upon  receipt by the  Trustee of an Issuer
Order, (i) two years from the later of issuance of the Security or the date such
Security (or any  predecessor)  was last  acquired  from an  "affiliate"  of the
Issuer  within  the  meaning  of Rule 144  under  the  Securities  Act,  (ii) in
connection with a sale made pursuant to the volume (and other  restrictions)  of
Rule 144 under the Securities Act following one year from such time, or (iii) in
connection with any sale in a transaction  registered  under the Securities Act,
provided that, if the legend is removed and the Security is subsequently held by
such an affiliate of the Issuer, the legend shall be reinstated.

         (b) Each Holder of a Security  agrees to  indemnify  the Issuer and the
Trustee  against any liability  that may result from the  transfer,  exchange or
assignment  of such  Holder's  security in  violation  of any  provision of this
Indenture and/or applicable United States Federal or state securities law.

         (c) The Trustee shall have no obligation or duty to monitor,  determine
or inquire as to compliance with any restrictions on transfer imposed under this
Indenture or under  applicable  law with respect to any transfer of any interest
in  any  Security   (including  any  transfers   between  or  among   Depositary
participants or beneficial owners of

                                      -22-

<PAGE>

interest  in any  Global  Security)  other  than  to  require  delivery  of such
certificates and other  documentation or evidence as are expressly  required by,
and to do so if and when expressly required by the terms of, this Indenture, and
to examine  the same to  determine  substantial  compliance  as to form with the
express requirements hereof.

                                  ARTICLE THREE

                                    COVENANTS

                  SECTION  3.1 Payment of  Principal  and  Interest.  The Issuer
covenants  and agrees that it will duly and  punctually  pay or cause to be paid
the  principal  of, and  interest  on,  each of the  Securities  at the place or
places, at the respective times and in the manner provided in the Securities and
this Indenture.  Interest on the Securities  shall be computed on the basis of a
360-day  year of twelve  30-day  months.  Each  instalment  of  interest  on the
Securities  may be paid by mailing  checks for such interest  payable to or upon
the written  order of the Holders of Securities  entitled  thereto as they shall
appear on the registry books of the Issuer.

                  SECTION 3.2  Written  Statement  to  Trustee.  The Issuer will
deliver to the Trustee, within 120 days after the end of each fiscal year of the
Issuer ending after the date hereof, an Officers'  Certificate,  stating that in
the course of the  performance by the signers of their duties as officers of the
Issuer they would  normally have knowledge of any default or  non-compliance  by
the Issuer in the  performance  or  fulfillment  of any  covenant,  agreement or
condition  contained  in  this  Indenture,  stating  whether  or not  they  have
knowledge of any such default or non-compliance (without regard to any period of
grace or requirement of notice provided hereunder),  and, if so, specifying each
such  default or  non-compliance  of which the signers  have  knowledge  and the
nature thereof.

         The Issuer shall deliver to the Trustee, as soon as possible and in any
event within five days after the Issuer

                                      -23-

<PAGE>

becomes aware of the occurrence of any Event of Default or an event which,  with
notice or the lapse of time or both,  would  constitute an Event of Default,  an
Officers'  Certificate  setting  forth the  details  of such Event of Default or
default and the action which the Issuer proposes to take with respect thereto.

                  SECTION 3.3 Corporate Existence. Subject to Article Eight, the
Issuer will do or cause to be done all things  necessary to preserve and keep in
full force and effect its corporate existence,  rights and franchises;  provided
that the Issuer shall not be required to preserve its corporate existence or any
such right or  franchise  if the Issuer shall  determine  that the  preservation
thereof is no longer  desirable in the conduct of its business and that the loss
thereof is not  disadvantageous  in any  material  respect to the Holders of the
Securities.

                  SECTION  3.4 Reports by the Issuer.  The Issuer  covenants  to
file with the  Trustee,  within 15 days after the Issuer is required to file the
same  with  the  SEC,  copies  of the  annual  reports  and of the  information,
documents, and other reports (or copies of such portions of any of the foregoing
as the SEC may from time to time by rules and regulations  prescribe)  which the
Issuer may be  required  to file with the SEC  pursuant to Section 13 or Section
15(d) of the Exchange Act, or if the Issuer is not required to file information,
documents, or reports pursuant to either of such sections, then to file with the
Trustee,  in accordance with rules and regulations  prescribed from time to time
by the SEC, such of the supplementary and periodic information,  documents,  and
reports which may be required pursuant to Section 13 of the Exchange Act; or, in
respect of a security listed and registered on a national securities exchange or
on NASDAQ as may be prescribed from time to time in such rules and  regulations.
At any  time  when the  Issuer  is not  subject  to  Section  13 or 15(d) of the
Exchange Act, upon request of Holders and  prospective  purchasers of Securities
or the Class A Common Stock issuable upon  conversion  thereof,  the Issuer will
promptly  furnish  or cause to be  furnished  to such  holders  and  prospective
purchasers, copies of the information required to be delivered to such holders

                                      -24-

<PAGE>

and prospective  purchasers of such securities pursuant to Rule 144A(d)(4) under
the  Securities  Act (or any  successor  provision  thereto)  in order to permit
compliance  with Rule 144A in  connection  with  resales by such holders of such
securities.  The Issuer will pay the  expenses of printing and  distributing  to
such holders and prospective purchasers all such documents.

                  Delivery of such  reports,  information  and  documents to the
Trustee is for  informational  purposes only and the  Trustee's  receipt of such
shall not constitute constructive notice of any information contained therein or
determinable  from  information   contained  therein,   including  the  Issuer's
compliance  with any of its  covenants  hereunder  (as to which the  Trustee  is
entitled to rely exclusively on Officers' Certificates).

                  SECTION 3.5 Waiver of Usury Defense.  The Issuer covenants (to
the extent that it may  lawfully  do so) that it shall not  assert,  plead (as a
defense or  otherwise)  or in any manner  whatsoever  claim (and shall  actively
resist any attempt to compel it to assert,  plead or claim) in any action,  suit
or  proceeding  that the interest  rate on the  Securities  violates  present or
future usury or other laws relating to the interest  payable on any indebtedness
and shall not otherwise  avail itself (and shall actively  resist any attempt to
compel it to avail itself) of the benefits or advantages of any such laws.

                  SECTION 3.6 Payment of Excess  Cash  Dividends.  If the Issuer
shall  declare  and pay  cash  dividends  on its  Class  A  Common  Stock  in an
annualized  per share amount which exceeds the greater of (i) the annualized per
share amount of the  immediately  preceding  cash dividend on its Class A Common
Stock (as adjusted to reflect any of the events listed in Sections 12.4 or 12.5)
and (ii)  15% of the  Last  Sale  Price  of the  Class A Common  Stock as of the
Trading Day immediately  preceding the date of declaration of such dividend (the
per share amount of any such per share  excess,  to the extent of such per share
excess,  being  herein  called an "Excess  Amount"),  then in any such event the
Holders shall have the right to receive, and the Issuer will pay to

                                      -25-

<PAGE>

each  such  Holder,  at the time of the  payment  of such  Class A Common  Stock
dividend, an amount equal to such Excess Amount (calculated by the Issuer on the
basis of the  number of  shares of Class A Common  Stock  that  would  have been
issued to a Holder upon  conversion of the Securities held by such Holder on the
record date for the payment of such  dividend)  unless the Holder  converts  and
receives  such  dividend as a holder of Class A Common  Stock.  The Issuer shall
give the Trustee written notice of the payment of Excess Amounts to the Holders.

                  SECTION 3.7  Registration  Rights.  The Issuer agrees that the
Holders  from  time  to  time  of  Registrable  Securities  (as  defined  in the
Registration  Rights Agreement) are entitled to the benefits of the Registration
Rights Agreement. Whenever in this Indenture there is mentioned, in any context,
the payment of interest on, or in respect of, any  Security,  such mention shall
be deemed to include mention of the payment of liquidated  damages on Securities
constituting  Registrable  Securities  as  contemplated  in  Section  3  of  the
Registration  Rights  Agreement  to the  extent  that,  in  such  context,  such
liquidated  damages are, were or would be payable in respect thereof pursuant to
the provisions of the Registration Rights Agreement.

                                  ARTICLE FOUR

                           REMEDIES OF THE TRUSTEE AND
                       SECURITYHOLDERS ON EVENT OF DEFAULT

                  SECTION  4.1  Event  of  Default   Defined;   Acceleration  of
Maturity; Waiver of Default. "Event of Default" with respect to Securities where
used herein,  means each one of the  following  events which shall have occurred
and be continuing  (whatever the reason for such Event of Default and whether it
shall be voluntary or involuntary or be effected by operation of law or pursuant
to any judgment,  decree or order of any court or any order,  rule or regulation
of any administrative or governmental body):

                                      -26-

<PAGE>

                  (a) default in the payment of any  instalment of interest upon
         any of the  Securities  as and  when  the  same  shall  become  due and
         payable, and continuance of such default for a period of 30 days; or

                  (b) default in the payment of all or any part of the principal
         of or premium,  if any, upon any of the Securities as and when the same
         shall become due and payable either at maturity, upon any redemption or
         acceleration, by declaration or otherwise; or

                  (c)  failure  on the part of the  Issuer to observe or perform
         any other of the  covenants or  agreements on the part of the Issuer in
         the Securities or in this  Indenture  contained for a period of 60 days
         after the date on which written notice specifying such failure, stating
         that such notice is a "Notice of Default"  hereunder and demanding that
         the Issuer  remedy the same,  shall  have been given by  registered  or
         certified mail, return receipt requested, to the Issuer by the Trustee,
         or to the  Issuer  and the  Trustee  by the  Holders of at least 25% in
         aggregate principal amount of the Outstanding Securities; or

                  (d) a court having  jurisdiction in the premises shall enter a
         decree or order for relief in  respect of the Issuer in an  involuntary
         case or proceeding  under any applicable  Federal or State  bankruptcy,
         insolvency,  reorganization  or other  similar law now or  hereafter in
         effect,  or a decree  or order  adjudging  the  Issuer  a  bankrupt  or
         insolvent,   approving   as   properly   filed   a   petition   seeking
         reorganization, assignment, adjustment or composition of, or in respect
         of, the Issuer under any applicable  Federal or State law or appointing
         a receiver, liquidator,  assignee, custodian, trustee, sequestrator (or
         similar  official)  of the  Issuer or for any  substantial  part of its
         property or ordering the winding up or liquidation of its affairs,  and
         such decree or order shall  remain  unstayed and in effect for a period
         of 60 consecutive days; or

                                      -27-

<PAGE>

                  (e) the Issuer shall  commence a voluntary  case or proceeding
         under  any  applicable   Federal  or  State   bankruptcy,   insolvency,
         reorganization  or other similar law now or hereafter in effect, or any
         other case or proceeding to be adjudicated a bankrupt or insolvent,  or
         consent to the entry of an order for relief in an  involuntary  case or
         proceeding   under  any   applicable   Federal  or  State   bankruptcy,
         insolvency,  reorganization or other similar law or to the commencement
         of any  bankruptcy or insolvency  case or proceeding  against it, or to
         the  filing  by  it  of  a  petition  or  answer  or  consent   seeking
         reorganization or relief under any applicable  Federal or State law, or
         consent to the filing of such petition or to the  appointment or taking
         possession by a receiver,  liquidator,  assignee, custodian, trustee or
         sequestrator (or similar official) of the Issuer or for any substantial
         part of its property,  or make any general  assignment  for the benefit
         of creditors, or the admission by it in writing of its inability to pay
         its debts  generally  as they become  due,  or the taking of  corporate
         action by the Issuer in furtherance of any such action.

                  If an Event of Default  occurs and is continuing  with respect
to the Securities,  then, and in each and every such case,  unless the principal
of all the  Securities  shall have already  become due and  payable,  either the
Trustee or the Holders of not less than 25% in aggregate principal amount of the
Securities then Outstanding  hereunder,  by notice in writing to the Issuer (and
to the Trustee if given by Securityholders), may declare the entire principal of
all the  Securities,  and the interest  accrued  thereon,  to be due and payable
immediately, and upon any such declaration the same shall become immediately due
and payable.  This provision,  however,  is subject to the condition that if, at
any time after the Securities  shall have been so declared due and payable,  and
before any  judgment or decree for the payment of the moneys due shall have been
obtained  or  entered as  hereinafter  provided,  the Issuer  shall pay or shall
deposit with the Trustee a sum  sufficient  to pay all matured  installments  of
interest upon all the  Securities  and the  principal of any and all  Securities
which shall have

                                      -28-

<PAGE>

become due otherwise  than by  acceleration  (with  interest upon such principal
and, to the extent that payment of such interest is enforceable under applicable
law,  on  overdue  installments  of  interest,  at the same  rate as the rate of
interest  specified in the  Securities,  to the date of such payment or deposit)
and such amount as shall be sufficient to cover  reasonable  compensation to the
Trustee and each predecessor  Trustee,  their respective  agents,  attorneys and
counsel, and all other expenses and liabilities incurred, and all advances made,
by the Trustee and each predecessor  Trustee except as a result of negligence or
bad faith, and if any and all Events of Default under the Indenture,  other than
the non-payment of the interest on and principal of Securities  which shall have
become due by acceleration,  shall have been cured, waived or otherwise remedied
as provided  herein--then and in every such case of such a cure the Holders of a
majority in aggregate  principal amount of the Securities then  Outstanding,  by
written  notice to the Issuer and to the  Trustee,  may waive all  defaults  and
rescind and annul such declaration and its  consequences,  but no such waiver or
rescission and annulment shall extend to or shall affect any subsequent  default
or shall impair any right consequent thereon.

                  SECTION 4.2 Collection of Indebtedness by Trustee; Trustee May
Prove Debt.  The Issuer  covenants that (a) in case default shall be made in the
payment  of any  instalment  of  interest  on any of the  Securities  when  such
interest  shall  have  become  due and  payable,  and such  default  shall  have
continued  for a period of 30 days or (b) in case  default  shall be made in the
payment of all or any part of the principal of or premium, if any, on any of the
Securities  when the same  shall  have  become  due and  payable,  whether  upon
maturity or upon any redemption or by declaration or otherwise, then upon demand
of the  Trustee,  the  Issuer  will pay to the  Trustee  for the  benefit of the
Holders of the  Securities  the whole amount that then shall have become due and
payable on all such Securities for principal,  premium, if any, or interest,  as
the case may be (with  interest  to the date of such  payment  upon the  overdue
principal and, to the extent that payment of such interest is enforceable  under
applicable law, on overdue installments

                                                                            -29-

<PAGE>

of  interest  at the  same  rate  as  the  rate  of  interest  specified  in the
Securities;  and in addition thereto, such further amount as shall be sufficient
to cover the costs and expenses of collection, including reasonable compensation
to the Trustee and each predecessor Trustee, their respective agents,  attorneys
and counsel,  and any expense and liabilities incurred,  and all advances made,
by the Trustee and each predecessor Trustee except as a result of its negligence
or bad faith.

                  Until such demand is made by the  Trustee,  the Issuer may pay
the  principal of and premium,  if any,  and interest on the  Securities  to the
registered Holders, whether or not the Securities be overdue.

                  In case the Issuer  shall fail  forthwith  to pay such amounts
upon such  demand,  the  Trustee,  in its own name and as  trustee of an express
trust, shall be entitled and empowered to institute any action or proceedings at
law or in  equity  for the  collection  of the sums so due and  unpaid,  and may
prosecute any such action or  proceedings  to judgment or final decree,  and may
enforce any such  judgment or final decree  against the Issuer or other  obligor
upon the  Securi  ties and  collect  in the  manner  provided  by law out of the
property of the Issuer or other obligor upon the Securities,  wherever situated,
the moneys adjudged or decreed to be payable.

                  In case there  shall be pending  proceedings  relative  to the
Issuer or any other  obligor  upon the  Securities  under Title 11 of the United
States Code or any other  applicable  Federal or state  bankruptcy,  insolvency,
reorganization or other similar law, or in case a receiver,  assignee or trustee
in bankruptcy or  reorganization,  liquidator,  sequestrator or similar official
shall have been appointed for or taken  possession of the Issuer or its property
or such other obligor, or in case of any other comparable  judicial  proceedings
relative to the Issuer or other obligor upon the Securities, or to the creditors
or property of the Issuer or such other obligor,  the Trustee,  irrespective  of
whether the principal of the Securities shall then be due and payable as therein
expressed or by

                                      -30-

<PAGE>

declaration or otherwise and irrespective of whether the Trustee shall have made
any demand  pursuant to the  provisions of this  Section,  shall be entitled and
empowered, by intervention in such proceedings or otherwise:

                  (a) to file and prove a claim or claims  for the whole  amount
         of principal, premium, if any, and interest owing and unpaid in respect
         of the Securities, and to file such other papers or documents as may be
         necessary  or  advisable  in order to have the  claims of the  Trustees
         (including  any claim for  reasonable  compensation  to the Trustee and
         each predecessor  Trustee,  and their respective agents,  attorneys and
         counsel,   and  for  reimbursement  of  all  expenses  and  liabilities
         incurred,  and all advances  made, by the Trustee and each  predecessor
         Trustee,  except as a result of  negligence  or bad  faith)  and of the
         Securityholders  allowed in any  judicial  proceedings  relative to the
         Issuer or other  obligor upon the  Securities,  or to the  creditors or
         property of the Issuer or such other obligor,

                  (b) unless  prohibited by applicable law and  regulations,  to
         vote on behalf of the Holders of the  Securities  in any  election of a
         trustee   or  a  standby   trustee  in   arrangement,   reorganization,
         liquidation  or other  bankruptcy or insolvency  proceedings  or person
         performing similar functions in comparable proceedings, and

                  (c) to  collect  and  receive  any  moneys  or other  property
         payable  or  deliverable  on any such  claims,  and to  distribute  all
         amounts received with respect to the claims of the  Securityholders and
         of  the  Trustee  on  their  behalf;  and  any  trustee,  receiver,  or
         liquidator, custodian or other similar official is hereby authorized by
         each of the  Securityholders  to make payments to the Trustee,  and, in
         the event that the  Trustee  shall  consent  to the making of  payments
         directly to the Securityholders,  to pay to the Trustee such amounts as
         shall be sufficient to cover  reasonable  compensation  to the Trustee,
         each predecessor Trustee

                                      -31-

<PAGE>

         and their  respective  agents,  attorneys  and  counsel,  and all other
         expenses  and  liabilities  incurred,  and all  advances  made,  by the
         Trustee and each  predecessor  Trustee except as a result of negligence
         or bad faith.

                  Nothing  herein  contained  shall be deemed to  authorize  the
Trustee to  authorize  or consent to or vote for or accept or adopt on behalf of
any  Securityholder  any  plan of  reorganization,  arrangement,  adjustment  or
caption  affecting  the  Securities or the rights of any Holder  thereof,  or to
authorize the Trustee to vote in respect of the claim of any  Securityholder  in
any such proceeding except, as aforesaid,  to vote for the election of a trustee
in bankruptcy or similar person.

                  All  rights of  action  and of  asserting  claims  under  this
Indenture, or under any of the Securities, may be prosecuted and enforced by the
Trustee  without  the  possession  of any of the  Securities  or the  production
thereof on any trial or other proceedings  relative thereto, and any such action
or  proceedings  instituted  by the Trustee  shall be brought in its own name as
trustee  of an express  trust,  and any  recovery  of  judgment,  subject to the
payment of the expenses,  disbursements  and  compensation of the Trustee,  each
predecessor Trustee and their respective agents and attorneys,  shall be for the
ratable benefit of the Holders of the Securities.

                  In any  proceedings  brought  by the  Trustee  (and  also  any
proceedings  involving the  interpretation of any provision of this Indenture to
which the Trustee  shall be a party) the Trustee  shall be held to represent all
the Holders of the Securities in respect of which such action was taken,  and it
shall not be necessary to make any Holders of the Securities parties to any such
proceedings.

                  SECTION 4.3 Application of Proceeds.  Any moneys  collected by
the Trustee  pursuant to this Article in respect of Securities  shall be applied
in the following order at the date or dates fixed by the Trustee and, in case of
the  distribution  of such  moneys on account of  principal  or  interest,  upon
presentation of the several Securities and

                                      -32-

<PAGE>

stamping (or otherwise  noting)  thereon the payment,  or issuing  Securities in
reduced  principal  amounts in exchange  for the  presented  Securities  if only
partially paid, or upon surrender thereof if fully paid:

                  FIRST:  To the payment of costs and expenses,
         including any and all amounts due the Trustee under
         Section 5.5;

                  SECOND: In case the principal of the Securities shall not have
         become and be then due and  payable,  to the payment of interest on the
         Securities in default in the order of the maturity of the  installments
         of such  interest,  with interest (to the extent that such interest has
         been  collected  by the  Trustee)  upon  the  overdue  installments  of
         interest  at the same  rate as the rate of  interest  specified  in the
         Securities,  such  payments to be made  ratably to the person  entitled
         thereto, without discrimination or preference;

                  THIRD:  In case the  principal  of the  Securities  shall have
         become and shall be then due and  payable,  to the payment of the whole
         amount then owing and unpaid  upon all the  Securities  for  principal,
         premium, if any, and interest, with interest upon the overdue principal
         and  premium,  if any,  and (to the extent that such  interest has been
         collected by the Trustee) upon overdue  installments of interest at the
         same rate as the rate of interest  specified in the Securities;  and in
         case such moneys shall be  insufficient to pay in full the whole amount
         so due and  unpaid  upon the  Securities,  then to the  payment of such
         principal,  premium,  if  any,  and  interest,  without  preference  or
         priority  of  principal  (and  premium,  if any) over  interest,  or of
         interest over principal (and premium,  if any), or of any instalment of
         interest over any other instalment of interest, or of any Security over
         any  other  Security,  ratably  to the  aggregate  of  such  principal,
         premium, if any, and accrued and unpaid interest; and

                                      -33-

<PAGE>

                  FOURTH: To the payment of the remainder, if any, to the Issuer
         or any other person lawfully entitled thereto.

                  SECTION 4.4 Suits for Enforcement. In case an Event of Default
has  occurred,  has not been  waived and is  continuing,  the Trustee may in its
discretion  proceed  to protect  and  enforce  the  rights  vested in it by this
Indenture by such  appropriate  judicial  proceedings  as the Trustee shall deem
most  effectual to protect and enforce any of such  rights,  either at law or in
equity or in bankruptcy or otherwise,  whether for the specific  enforcement  of
any covenant or agreement  contained in this Indenture or in aid of the exercise
of any  power  granted  in this  Indenture  or to  enforce  any  other  legal or
equitable right vested in the Trustee by this Indenture or by law.

                  SECTION  4.5   Restoration   of  Rights  or   Abandonment   of
Proceedings.  In case the Trustee or any Securityholder  shall have proceeded to
enforce  any right under this  Indenture  and such  proceedings  shall have been
discontinued  or  abandoned  for any  reason,  or  shall  have  been  determined
adversely to the Trustee or to such Securityholder, then and in every such case,
subject to any determination in such proceeding, the Issuer, the Trustee and the
Securityholders  shall be restored  severally and  respectively  to their former
positions and rights hereunder,  and thereafter all rights,  remedies and powers
of the Issuer, the Trustee and the  Securityholders  shall continue as though no
such proceedings had been taken.

                  SECTION  4.6  Limitations  on Suits by  Security  holders.  No
Holder of any  Security  shall  have any right by virtue or by  availing  of any
provision of this Indenture to institute any action or  proceeding,  judicial or
otherwise,  at law or in equity or in bankruptcy  or otherwise  upon or under or
with respect to this Indenture, or for the appoint ment of a trustee,  receiver,
liquidator,  custodian  or  other  similar  official  or for  any  other  remedy
hereunder, unless such Holder previously shall have given to the Trustee written
notice of a continuing  Event of Default as herein before  provided,  and unless
also the Holders of not less

                                      -34-

<PAGE>

than 25% in aggregate  principal amount of the Securities then Outstanding shall
have made written request upon a Responsible Officer of the Trustee to institute
such action or proceedings  in its own name as trustee  hereunder and shall have
offered to the Trustee  indemnity  satisfactory  to it as it may require against
the costs,  expenses and  liabilities to be incurred  therein or thereby and the
Trustee  for 45 days after its  receipt  of such  notice,  request  and offer of
indemnity  shall have failed to institute any such action or proceedings  and no
direction  inconsistent  with such  written  request  shall have been given to a
Responsible  Officer of the Trustee pursuant to Section 4.9; it being understood
and intended,  and being  expressly  covenanted by the Holder of every  Security
with every other Holder of the Securities  and the Trustee,  that no one or more
Holders of Securities  shall have any right in any manner  whatever by virtue or
by availing of any provision of this  Indenture to affect,  disturb or prejudice
the  rights of any other  Holder of  Securities,  or to obtain or seek to obtain
priority  over or  preference  to any other such  Holder or to enforce any right
under this  Indenture,  except in the manner herein  provided and for the equal,
ratable and common benefit of all Holders of Securities.  For the protection and
enforcement of the provisions of this Section, each and every Securityholder and
the Trustee shall be entitled to such relief as can be given either at law or in
equity.

                  SECTION 4.7 Unconditional Right of Security holders to Receive
Principal,  Premium and  Interest,  to Convert and to Institute  Certain  Suits.
Notwithstanding  any other  provision in this Indenture and any provision of any
Security,  the right of any Holder of any  Security  to  receive  payment of the
principal of and premium, if any, and inter est on such Security on or after the
respective due dates  expressed in such Security (or, in the case of redemption,
on the  applicable  Redemption  Date or  Repurchase  Date),  or to convert  such
Security  in  accordance  with  Article  Twelve,  or to  institute  suit for the
enforcement of any such payment on or after such  respective  dates,  or for the
enforcement of such conversion right, shall not be impaired or affected

                                      -35-

<PAGE>

without the written consent of such Holder, with a copy thereof to the Trustee.

                  SECTION 4.8 Powers and Remedies Cumulative;  Delay or Omission
Not Waiver of Default.  Except as  provided in Sections  2.7, no right or remedy
herein  conferred upon or reserved to the Trustee or to the  Securityholders  is
intended  to be  exclusive  of any other  right or remedy,  and every  right and
remedy shall,  to the extent  permitted by law, be cumulative and in addition to
every other right and remedy given hereunder or now or hereafter existing at law
or in equity or  otherwise.  The  assertion or employment of any right or remedy
hereunder,  or  otherwise,   shall  not  prevent  the  concurrent  assertion  or
employment of any other appropriate right or remedy.

                  No delay or omission of the Trustee or of any Holder of any of
the Securities to exercise any right or power accruing upon any Event of Default
occurring and  continuing  as aforesaid  shall impair any such right or power or
shall  be  construed  to  be a  waiver  of  any  such  Event  of  Default  or an
acquiescence  therein; and, subject to Section 4.6, every power and remedy given
by this  Indenture  or by law to the  Trustee or to the  Securityholders  may be
exercised from time to time, and as often as shall be deemed  expedient,  by the
Trustee or by the Securityholders, as the case may be.

                  SECTION  4.9  Control  by  Securityholders.  The  Holders of a
majority in aggregate principal amount of the Securities at the time Outstanding
shall  have the right to  direct  in  writing  the  time,  method,  and place of
conducting any proceeding for any remedy available to the Trustee, or exercising
any  trust or  power  conferred  on the  Trustee;  provided  that  such  written
direction  shall not be otherwise than in accordance with law and the provisions
of this  Indenture;  and provided,  further,  that (subject to the provisions of
Section  5.1) the  Trustee  shall  have the right to  decline to follow any such
direction if the Trustee,  being advised by counsel,  shall  determine  that the
action or proceeding so directed may expose the Trustee to personal liability or
if the Trustee in good faith by its board of

                                      -36-

<PAGE>

directors or the executive committee thereof shall so determine that the actions
or  forbearances  specified  in or  pursuant to such  direction  would be unduly
prejudicial  to the  interests of Holders of the  Securities  not joining in the
giving of said direction,  it being understood that (subject to Section 5.1) the
Trustee  shall  have  no  duty to  ascertain  whether  or not  such  actions  or
forbearances are unduly prejudicial to such Holders.

                  Nothing  in this  Indenture  shall  impair  the  right  of the
Trustee in its  discretion  to take any action  deemed proper by the Trustee and
which is not inconsistent with such direction by Securityholders.

                  SECTION 4.10 Waiver of Past Defaults. Prior to the declaration
of the maturity of the  Securities  as provided in Section 4.1, the Holders of a
majority in aggregate principal amount of the Securities at the time Outstanding
may on behalf of the  Holders of all the  Securities  waive any past  default or
Event of Default hereunder and its consequences,  except a default in respect of
a covenant or provision  hereof which cannot be modified or amended  without the
consent of the Holder of each Security affected (including,  without limitation,
the provisions with respect to payment of principal of and premium,  if any, and
interest on such  Security or with respect to conversion  of such  Security).  A
copy of any such waiver or consent shall be delivered to the Trustee.

                  Upon any such waiver, such default shall cease to exist and be
deemed to have been  cured and not to have  occurred,  and any Event of  Default
arising  therefrom shall be deemed to have been cured,  and not to have occurred
for every  purpose of this  Indenture;  but no such waiver  shall  extend to any
subsequent or other  default or Event of Default or impair any right  consequent
thereon.

                  SECTION  4.11  Trustee  to Give  Notice  of  Default,  But May
Withhold in Certain  Circumstances.  The Trustee shall, at the Issuer's expense,
transmit  to the  Holders  of  Securities,  as the names and  addresses  of such
Holders appear on the registry books, notice by mail of all defaults

                                      -37-

<PAGE>

known to a  Responsible  Officer of the Trustee,  such notice to be  transmitted
within 90 days after the  occurrence  thereof,  unless such defaults  shall have
been cured before the giving of such notice (the term  "default"  or  "defaults"
for the  purposes  of this  Section  being  hereby  defined to mean any event or
condition  which is, or with  notice or lapse of time or both would  become,  an
Event of Default);  provided that,  except in the case of default in the payment
of the  principal of or premium,  if any, or interest on any of the  Securities,
the Trustee shall be protected in withholding  such notice if and so long as the
board of directors,  the executive committee,  or a trust committee of directors
or trustees and/or Responsible  Officers of the Trustee in good faith determines
that the withholding of such notice is in the interests of the Securityholders.

                  SECTION 4.12 Right of Court to Require  Filing of  Undertaking
to Pay  Costs.  All  parties to this  Indenture  agree,  and each  Holder of any
Security by his  acceptance  thereof  shall be deemed to have  agreed,  that any
court may in its  discretion  require,  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,  suffered  or omitted by it as  Trustee,  the filing by any party
litigant in such suit other than the Trustee of an  undertaking to pay the costs
of such suit, and that such court may in its discretion assess reasonable costs,
including attorneys' fees, against any party litigant in such suit including the
Trustee,  having  due  regard  to the  merits  and good  faith of the  claims or
defenses made by such party  litigant;  but the provisions of this Section shall
not apply to any suit  instituted by the Trustee,  to any suit instituted by any
Securityholder  or group of  Securityholders  holding in the aggregate more than
10% in aggregate principal amount of the Securities at the time Outstanding,  or
to any suit instituted by any  Securityholder for the enforcement of the payment
of the  principal  of or  interest  on any  Security  on or  after  the due date
expressed  in such  Security  or for the  enforcement  of a right to convert any
Security in accordance with Article Twelve.

                                      -38-

<PAGE>

                  SECTION  4.13  Waiver of Stay or  Extension  Laws.  The Issuer
covenants  (to the extent  that it may  lawfully  do so) that it will not at any
time  insist  upon,  or plead,  or in any  manner  whatsoever  claim or take the
benefit or advantage of, any stay or extension law wherever  enacted,  now or at
any time hereafter in force,  which may affect the covenants or the  performance
of this  Indenture;  and the Issuer (to the extent  that it may  lawfully do so)
hereby  expressly  waives all benefit or advantage of any such law and covenants
that it will not  hinder,  delay or impede  the  execution  of any power  herein
granted to the Trustee,  but will suffer and permit the  execution of every such
power as though no such law had been enacted.

                                  ARTICLE FIVE

                             CONCERNING THE TRUSTEE

                  SECTION 5.1 Duties and Responsibilities of the Trustee; During
Default;  Prior to Default.  With  respect to the Holders of  Securities  issued
hereunder, the Trustee, prior to the occurrence of an Event of Default and after
the  curing or  waiving  of all  Events  of  Default  which  may have  occurred,
undertakes to perform such duties and only such duties as are  specifically  set
forth in this  Indenture.  In case an  Event  of  Default  with  respect  to the
Securities has occurred and is continuing  (which has not been cured or waived),
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 their  exercise,  as a
prudent person would exercise or use under the  circumstances  in the conduct of
such person's own affairs.

                  No provision of this  Indenture  shall be construed to relieve
the Trustee from  liability  for its own  negligent  action,  its own  negligent
failure to act or its own wilful misconduct or bad faith, except that

                  (a) prior to the  occurrence  of an Event of Default and after
         the  curing or waiving  of all such  Events of  Default  which may have
         occurred:

                                      -39-

<PAGE>

                           (i) the duties and  obligations  of the Trustee  with
                  respect  to  Securities  shall  be  determined  solely  by the
                  express  provisions of this  Indenture,  and the Trustee shall
                  not be liable  except for the  performance  of such duties and
                  obligations as are  specifically  set forth in this Indenture,
                  and no implied  covenants  or  obligations  shall be read into
                  this Indenture against the Trustee; and

                           (ii) in the  absence  of bad faith on the part of the
                  Trustee, the Trustee may conclusively rely, as to the truth of
                  the statements and the correct ness of the opinions  expressed
                  therein,   upon   any   resolution,    statement,    officer's
                  certificate,  or any other certificate,  instrument or opinion
                  furnished to the Trustee and conforming to the requirements of
                  this  Indenture;  but in the  case  of  any  such  statements,
                  certificates  or opinions  which by any  provision  hereof are
                  specifically  required to be  furnished  to the  Trustee,  the
                  Trustee shall be under a duty to examine the same to determine
                  whether  or not  they  conform  to the  requirements  of  this
                  Indenture;

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

                  (c) the Trustee shall not be liable with respect to any action
         taken or omitted to be taken by it in good faith in accordance with the
         direction  of Holders  pursuant  to Section  4.9  relating to the time,
         method and place of conducting any proceeding for any remedy  available
         to the Trustee,  or exercising  any trust or power  conferred  upon the
         Trustee, under this Indenture.

                  None  of the  provisions  contained  in this  Indenture  shall
require the Trustee to expend or risk its own funds or otherwise  incur personal
financial liability in the

                                      -40-

<PAGE>

performance  of any of its  duties or in the  exercise  of any of its  rights or
powers,  if there shall be reasonable ground for believing that the repayment of
such funds or  adequate  indemnity  against  such  liability  is not  reasonably
assured to it.

                  SECTION 5.2  Certain Rights of the Trustee.
Subject to Section 5.1:

                  (a) the Trustee may  conclusively  rely and shall be protected
         in acting or  refraining  from  acting upon any  resolution,  Officers'
         Certificate or any other certificate,  statement,  instrument, opinion,
         report, notice,  request,  direction,  consent, order, bond, debenture,
         note, coupon,  security or other paper or document believed by it to be
         genuine and to have been  signed or  presented  by the proper  party or
         parties;

                  (b) any  request,  direction,  order or demand  of the  Issuer
         mentioned  herein  shall  be  sufficiently  evidenced  by an  Officers'
         Certificate  (unless  other  evidence  in  respect  thereof  be  herein
         specifically prescribed);  and any resolution of the Board of Directors
         may be  evidenced  to the Trustee by a copy  thereof  certified  by the
         Secretary or an Assistant Secretary of the Issuer;

                  (c) the Trustee may consult with  counsel of its  selection at
         the expense of the Issuer and any advice or Opinion of Counsel shall be
         full and complete authorization and protection in respect of any action
         taken,  suffered or omitted to be taken by it  hereunder  in good faith
         and in accordance with such advice or Opinion of Counsel;

                  (d) the Trustee  shall be under no  obligation to exercise any
         of the trusts or powers vested in it by this  Indenture at the request,
         order  or  direction  of  any of the  Securityholders  pursuant  to the
         provisions of this Indenture,  unless such  Securityholders  shall have
         offered  to the  Trustee  security  or  indemnity  satisfactory  to the
         Trustee against the costs, expenses

                                      -41-

<PAGE>

         and liabilities which might be incurred therein or thereby;

                  (e) the  Trustee  shall not be liable  for any  action  taken,
         suffered  or  omitted  by it in good  faith  and  believed  by it to be
         authorized or within the discretion, rights or powers conferred upon it
         by this Indenture;

                  (f) prior to the  occurrence of an Event of Default  hereunder
         and after the curing or waiver of all Events of  Default,  the  Trustee
         shall not be bound to make any investigation  into the facts or matters
         stated in any resolution,  certificate, statement, instrument, opinion,
         report, notice,  request,  consent, order, approval,  appraisal,  bond,
         debenture,  note, coupon,  security,  or other paper or document unless
         requested  in  writing  so to do by  the  Holders  of not  less  than a
         majority  in  aggregate   principal   amount  of  the  Securities  then
         Outstanding,   but  a  Responsible  Officer  of  the  Trustee,  in  its
         discretion,  may make such further inquiries or investigation into such
         facts or matters as it may see fit, and, if the Trustee shall determine
         to make such inquiry or investigation,  it shall be entitled to examine
         the books,  records and premises of the Issuer,  personally or by agent
         or attorney;  provided that, if the payment within a reasonable time to
         the Trustee of the costs, expenses or liabilities likely to be incurred
         by it in the  making of such  investigation  is, in the  opinion of the
         Trustee, not reasonably assured to the Trustee by the security afforded
         to it by the terms of this Indenture, the Trustee may require indemnity
         satisfactory  to the Trustee  against such expenses or liabilities as a
         condition to proceeding;  the expenses of every such examination  shall
         be paid by the  Issuer or, if paid by the  Trustee  or any  predecessor
         trustee, shall be repaid by the Issuer upon demand;

                  (g) the  Trustee  may  execute  any of the  trusts  or  powers
         hereunder  or perform  any duties  hereunder  either  directly or by or
         through agents or attorneys not

                                      -42-

<PAGE>

         regularly in its employ and the Trustee  shall not be  responsible  for
         any  misconduct or negligence on the part of any such agent or attorney
         appointed with due care by it hereunder;

                  (h) the  Trustee  shall not be  deemed  to have  notice of any
         Default or Event of Default unless a Responsible Officer of the Trustee
         has  actual  knowledge  thereof or unless  written  notice of any event
         which is in fact such a  default  is  received  by the  Trustee  at the
         Corporate Trust Office of the Trustee,  and such notice  references the
         Securities and this Indenture; and

                  (i)  the  rights,  privileges,   protections,  immunities  and
         benefits given to the Trustee, including, without limitation, its right
         to be  indemnified,  are extended to, and shall be enforceable  by, the
         Trustee  in  each  of its  capacities  hereunder,  and to  each  agent,
         custodian and other Person employed to act hereunder.

                  SECTION 5.3 Trustee Not Responsible for Recitals,  Disposition
of Securities or Application of Proceeds Thereof.  The recitals contained herein
and in the Securi ties,  except the Trustee's  certificates  of  authentication,
shall be taken as the  statements  of the  Issuer,  and the  Trustee  assumes no
responsibility   for  the   correctness  of  the  same.  The  Trustee  makes  no
representation  as to the validity or  sufficiency  of this  Indenture or of the
Securi ties. The Trustee shall not be accountable  for the use or application by
the Issuer of any of the Securities or of the proceeds thereof.

                  SECTION   5.4   Trustee   and  Agents  May  Hold   Securities;
Collections, etc.. The Trustee or any agent of the Issuer or the Trustee, in its
individual or any other capacity,  may become the owner or pledgee of Securities
with the same rights it would have if it were not the Trustee or such agent and,
subject to Section 5.8, may otherwise deal with the Issuer and receive, collect,
hold and retain

                                      -43-

<PAGE>

collections  from the Issuer  with the same  rights it would have if it were not
the Trustee or such agent.

                  SECTION 5.5  Compensation and  Indemnification  of Trustee and
Its Prior Claim. The Issuer covenants and agrees to pay to the Trustee from time
to time, and the Trustee shall be entitled to, such  compensation as the Company
and the Trustee  shall from time to time agree in writing for all services  that
the Trustee shall provide hereunder (which  compensation shall not be limited by
any  provision of law in regard to the  compensation  of a trustee of an express
trust) and the Issuer  covenants  and agrees to pay or reimburse the Trustee and
each  predecessor  Trustee  upon  its  request  for  all  reasonable   expenses,
disbursements  and advances incurred or made by or on behalf of it in accordance
with any of the provisions of this Indenture (including the compensation and the
expenses and  disbursements  of its counsel and of all agents and other  persons
not regularly in its employ) except any such expense, disbursement or advance as
may arise  from its  negligence  or bad  faith.  The Issuer  also  covenants  to
indemnify the Trustee and each predecessor  Trustee for, and to hold it harmless
against,  any loss, damage,  claim,  liability or expense including taxes (other
than taxes based upon,  measured by or determined by the income of the Trustee),
incurred  without  negligence  or bad  faith on its part,  arising  out of or in
connection with the acceptance or administration of this Indenture or the trusts
hereunder and its duties  hereunder,  including but not limited to the costs and
expenses  of  defending  itself  against  or  investigating  any claim  (whether
asserted  by the  Company,  any  Holder or any other  Person)  or  liability  in
connection  with the  exercise  or  performance  of any of its  powers or duties
hereunder.  The  obligations  of the Issuer under this Section to compensate and
indemnify the Trustee and each  predecessor  Trustee and to pay or reimburse the
Trustee and each predecessor  Trustee for expenses,  disbursements  and advances
shall  constitute  additional  indebtedness  hereunder  and  shall  survive  the
satisfaction and discharge of this Indenture. Such additional indebtedness shall
be a senior claim to that of the Securities  upon all property and funds held or
collected by the Trustee as such, except funds held in trust

                                      -44-

<PAGE>

for the payment of principal of or interest on  particular  Securities,  and the
Securities are hereby subordinated to such senior claim. When the Trustee incurs
expenses or renders services in connection with an Event of Default specified in
Section 4.1 or in connection with Article Four hereof,  the expenses  (including
the reasonable  fees and expenses of its counsel) and the  compensation  for the
service  in  connection   therewith  are  intended  to  constitute  expenses  of
administration under any bankruptcy law.

                  SECTION 5.6 Right of Trustee to Rely on Officers' Certificate,
etc..  Subject to Sections 5.1 and 5.2,  whenever in the  administration  of the
trusts of this Indenture the Trustee shall deem it necessary or desirable that a
matter be proved or  established  prior to taking or  suffering  or omitting any
action hereunder, such matter unless other evidence in respect thereof be herein
specifically  prescribed)  may, in the absence of negligence or bad faith on the
part of the Trustee,  be deemed to be conclusively  proved and established by an
Officers'  Certificate  delivered to the Trustee,  and such certificate,  in the
absence of  negligence  or bad faith on the part of the  Trustee,  shall be full
warrant to the Trustee for any action taken, suffered or omitted by it under the
provisions of this Indenture upon the faith thereof.

                  SECTION 5.7 Persons  Eligible for Appointment as Trustee.  The
Trustee  hereunder  shall at all  times be a  corporation  organized  and  doing
business  under the laws of the United  States of America or of any State or the
District of Columbia.  The Trustee and its direct parent shall at all times have
a combined capital and surplus of at least $50,000,000,  and which is authorized
under such laws to exercise corporate trust powers and is subject to supervision
or  examination  by Federal,  State or District of Columbia  authority.  If such
corporation publishes reports of condition at least annually, pursuant to law or
to the requirements of the aforesaid  supervising or examining  authority,  then
for the  purposes  of this  Section,  the  combined  capital and surplus of such
corporation  shall be deemed to be its combined capital and surplus as set forth
in its most recent report of condition so published. In

                                      -45-

<PAGE>

case at any time the Trustee shall cease to be eligible in  accordance  with the
provisions of this Section,  the Trustee shall resign  immediately in the manner
and with the effect specified in Section 5.8.

                  The  provisions of this Section 5.7 are in  furtherance of and
subject to Section 310(a) of the TIA.

                  SECTION 5.8 Resignation and Removal;  Appointment of Successor
Trustee.  (a) The  Trustee may at any time  resign by giving  written  notice of
resignation to the Issuer. Upon receiving such notice of resignation, the Issuer
shall promptly appoint a successor  trustee by written  instrument in duplicate,
executed by authority  of the Board of  Directors,  one copy of each  instrument
shall be  delivered  to the  resigning  Trustee  and one  copy to the  successor
trustee.  If no successor trustee shall have been so appointed and have accepted
appointment  within 30 days after the giving of such notice of resignation,  the
resigning  trustee may  petition  any court of  competent  jurisdiction  for the
appointment of a successor  trustee,  or any Security holder who has been a bona
fide Holder of a Security or Securities for at least six months may,  subject to
the  provisions of Section  4.12, on behalf of himself and all others  similarly
situated,  petition any such court for the appointment of a successor trustee at
the expense of the Issuer. Such court may thereupon,  after such notice, if any,
as it may deem proper and prescribe, appoint a successor trustee.

                  (b) If at any time any of the following shall occur:

                (i) the  Trustee  shall fail to comply  with the pro  visions of
         Section 310(b) of the TIA after written request  therefor by the Issuer
         or by any  Securityholder who has been a bona fide Holder of a Security
         or Securities for at least six months; or

               (ii)  the Trustee shall  cease to be  eligible in accordance with
         the provisions of Section 5.7 and shall

                                      -46-

<PAGE>

         fail to resign after written  request  therefor by the Issuer or by any
         Securityholders;

              (iii) the Trustee  shall become  incapable of acting,  or shall be
         adjudged a bankrupt or  insolvent,  or a receiver or  liquidator of the
         Trustee or of its property  shall be appointed,  or any public  officer
         shall  take  charge or control of the  Trustee  or of its  property  or
         affairs for the purpose of rehabilitation, conservation or liquidation;

then,  in any such  case,  the  Issuer may  remove  the  Trustee  and  appoint a
successor trustee by written instrument, in duplicate,  executed by order of the
Board  of  Directors  of the  Issuer,  one  copy of  which  instrument  shall be
delivered to the Trustee so removed and one copy to the  successor  trustee,  or
subject to the  provisions of Section 4.12,  any  Securityholder  who has been a
bona fide  Holder of a  Security  or  Securities  for at least six months may on
behalf of  himself  and all others  similarly  situated,  petition  any court of
competent  jurisdiction  for the removal of the Trustee and the appointment of a
successor  trustee.  Such court may thereupon,  after such notice, if any, as it
may deem  proper and  prescribe,  remove the  Trustee  and  appoint a  successor
trustee.

                  (c) The Holders of a majority in aggregate principal amount of
the  Securities at the time  Outstanding  may at any time remove the Trustee and
appoint a successor  trustee by  delivering  to the  Trustee so removed,  to the
successor  trustee so appointed  and to the Issuer the evidence  provided for in
Section 6.1 of the action in that regard taken by the Securityholders.

                  (d)  Any  resignation  or  removal  of  the  Trustee  and  any
appointment  of a successor  trustee  pursuant to any of the  provisions of this
Section  5.8 shall  become  effective  upon  acceptance  of  appointment  by the
successor trustee as provided in Section 5.9.

                  (e) The Issuer shall give notice of each resigna tion and each
removal of the Trustee and each appointment of

                                      -47-

<PAGE>

a successor trustee by mailing written notice of such event by first-class mail,
postage  prepaid,  to the  Holders of  Securities  affected  as their  names and
addresses appear in the Security register. Each notice shall include the name of
the successor trustee and the address of its principal corporate trust office.

                  SECTION 5.9  Acceptance of  Appointment by Succes sor Trustee.
Any  successor  trustee  appointed as provided in Section 5.8 shall  execute and
deliver to the Issuer and to its  predecessor  trustee an  instrument  accepting
such  appointment  hereunder,  and thereupon the  resignation  or removal of the
predecessor  trustee shall become effective and such successor trustee,  without
any  further  act,  deed or  conveyance,  shall  become  vested with all rights,
powers, duties and obligations of its predecessor hereunder, with like effect as
if originally named as trustee herein; but, nevertheless, on the written request
of the Issuer or of the  successor  trustee,  upon  payment of its charges  then
unpaid,  the trustee  ceasing to act shall,  subject to Section 9.4, pay over to
the  successor  trustee  all moneys at the time held by it  hereunder  and shall
execute and deliver an instrument  prepared by the Issuer  transferring  to such
successor trustee all such rights, powers, duties and obligations.  Upon request
of any such successor trustee,  the Issuer shall execute any and all instruments
in  writing  for more fully and  certainly  vesting  in and  confirming  to such
successor trustee all such rights and powers.  Any trustee ceasing to act shall,
nevertheless,  retain a prior claim upon all property or funds held or collected
by such trustee to secure any amounts then due it pursuant to the  provisions of
Section 5.5.

                  Upon  acceptance  of  appointment  by a  successor  trustee as
provided  in  this  Section  5.9,  the  Issuer  shall  mail  notice  thereof  by
first-class  mail to the Holders of Securities  at their last  addresses as they
shall appear in the Security  register.  If the  acceptance  of  appointment  is
substantially  contemporaneous with the resignation,  then the notice called for
by the preceding  sentence may be combined with the notice called for by Section
5.8. If the Issuer fails to mail such notice within 10 days after acceptance of

                                      -48-

<PAGE>

appointment  by the successor  trustee,  the successor  trustee shall cause such
notice to be mailed at the expense of the Issuer.

                  SECTION 5.10 Merger,  Conversion,  Consolidation or Succession
to Business of Trustee.  Any corporation into which the Trustee may be merged or
converted or with which it may be  consolidated,  or any  corporation  resulting
from any merger,  conversion  or  consolidation  to which the Trustee shall be a
party,  or any  corporation  succeeding to the cor porate trust  business of the
Trustee,  shall be the successor of the Trustee  hereunder without the execution
or  filing  of any paper or any  further  act on the part of any of the  parties
hereto,  anything  herein to the contrary  notwithstanding;  provided  that such
corporation shall be qualified under the provisions of Section 310(b) of the TIA
and eligible under the provisions of Section 5.7.

                  In  case at the  time  such  successor  to the  Trustee  shall
succeed to the trusts created by this Indenture any of the Securities shall have
been  authenticated  but not  delivered,  any such  successor to the Trustee may
adopt the certificate of authentication  of any predecessor  trustee and deliver
such  Securities  so  authenticated;  and,  in  case  at  that  time  any of the
Securities shall not have been authen ticated,  any successor to the Trustee may
authenticate such Securities either in the name of any predecessor  hereunder or
in the name of the  successor  trustee;  and in all such cases such  certificate
shall have the full force  which it is  anywhere  in the  Securities  or in this
Indenture provided that the certificate of the Trustee shall have; provided that
the right to adopt the certificate of authentication of any predecessor  trustee
or to  authenticate  Securities  of any  series  in the name of any  predecessor
trustee shall apply only to its successor or successors by merger, conversion or
consolidation.

                                      -49-

<PAGE>

                                   ARTICLE SIX

                         CONCERNING THE SECURITYHOLDERS

                  SECTION 6.1 Evidence of Action Taken by Security holders.  Any
request,  demand,  authorization,  direction,  notice,  consent, waiver or other
action provided by this Indenture to be given or taken by Securityholders may be
embodied in and evidenced by one or more  instruments of  substantially  similar
tenor signed by such  Securityholders in person or by an agent duly appointed in
writing;  and, except as herein otherwise expressly provided,  such action shall
become  effective  when such  instrument  or  instruments  are  delivered to the
Trustee.  Proof of execution of any such  instrument or of a writing  appointing
any such  agent  shall be  sufficient  for any  purpose  of this  Indenture  and
(subject to  Sections  5.1 and 5.2)  conclusive  in favor of the Trustee and the
Issuer, if made in the manner provided in this Article.

                  SECTION 6.2 Proof of Execution of  Instruments  and of Holding
of  Securities.  Subject  to  Sections  5.1 and  5.2,  the  fact and date of the
execution of any instrument by any  Securityholder or his agent or proxy, or the
authority of such an agent or proxy to execute such an instrument  may be proved
(i) by the affidavit of a witness of such execution,  (ii) by a certificate of a
notary public (or other officer  authorized  by law to take  acknowledgments  of
deeds) as to such execution,  or (iii) in accordance with such reasonable  rules
and  regulations  as may be prescribed by the Trustee or in such manner as shall
be reasonably  satisfactory to the Trustee.  The holding of Securities  shall be
proved by the Security register or by a certificate of the registrar thereof.

                  SECTION  6.3  Holders to Be  Treated  as Owners.  Prior to due
presentment of a Security for registration of transfer, the Issuer, the Trustee,
any  Agent and any agent of the  Issuer  or the  Trustee  may deem and treat the
person in whose name any Security shall be registered upon the Security register
as the absolute  owner of such Security  (whether or not such Security  shall be
overdue and

                                      -50-

<PAGE>

notwithstanding  any  notation of ownership  or other  writing  thereon) for the
purpose of receiving  payment of or on account of the principal of and,  subject
to the provisions of this Indenture, interest on such Security and for all other
purposes;  and  neither the Issuer nor the Trustee nor any Agent or agent of the
Issuer or the Trustee shall be affected by any notice to the contrary.  All such
payments so made to any such person, or upon his order,  shall be valid, and, to
the extent of the sum or sums so paid,  effectual to satisfy and  discharge  the
liability for moneys payable upon any such Security.

                  SECTION 6.4 Securities Owned by Issuer Deemed Not Outstanding.
In  determining  whether  the  Holders  of the  requisite  principal  amount  of
Outstanding Securities have concurred in any direction,  consent or waiver under
this Indenture, Securities which are owned by the Issuer or any other obligor on
the  Securities or any Affiliate of the Issuer or of such other obligor shall be
disregarded  and  deemed  not to be  Outstanding  for the  purpose  of any  such
determination,  except that for the purpose of  determining  whether the Trustee
shall be  protected  in relying on any such  direction,  consent or waiver  only
Securities which the Trustee knows are so owned shall be so disregarded.  Securi
ties so  owned  which  have  been  pledged  in good  faith  may be  regarded  as
Outstanding  if the pledgee  establishes to the  satisfaction  of the Trustee in
writing the pledgee's  right so to act with respect to such  Securities and that
the pledgee is not the Issuer or any other  obligor upon the  Securities  or any
Affiliate  of the  Issuer or of such other  obligor.  In case of a dispute as to
such right,  the advice of counsel  shall be full  protection  in respect of any
decision made by the Trustee in accordance with such advice. Upon request of the
Trustee,  the  Issuer  shall  furnish  to  the  Trustee  promptly  an  Officers'
Certificate listing and identifying all Securities,  if any, known by the Issuer
to be owned or held by or for the account of any of the above-described Persons;
and,  subject to Sections 5.1 and 5.2,  the Trustee  shall be entitled to accept
such Officers' Certificate as conclusive evidence of the facts therein set forth
and of the fact that all Securities not listed therein are  Outstanding  for the
purpose of any such determination.

                                      -51-

<PAGE>

                  SECTION 6.5 Right of Revocation  of Action Taken.  At any time
prior to (but not after) the  evidencing to the Trustee,  as provided in Section
6.1, of the taking of any action by the Holders of the  percentage  in aggregate
principal  amount of the  Securities  specified in this  Indenture in connection
with such action,  any Holder of a Security the serial  number of which is shown
by the evidence to be included  among the serial  numbers of the  Securities the
Holders of which have  consented to such action may, by filing written notice at
the  Corporate  Trust  Office  and upon proof of  holding  as  provided  in this
Article,  revoke such action so far as concerns such  Security.  Except as afore
said any such action taken by the Holder of any Security shall be conclusive and
binding upon such Holder and upon all future Holders and owners of such Security
and  of any  Securities  issued  in  exchange  or  substitution  therefor  or on
registration or transfer thereof, irrespective of whether or not any notation in
regard thereto is made upon any such  Security.  Any action taken by the Holders
of the percentage in aggregate  principal amount of the Securities  specified in
this Indenture in connection with such action shall be conclusively binding upon
the Issuer, the Trustee and the Holders of all the Securities.

                  SECTION 6.6 Record Date for Consents  and Waivers.  The Issuer
may,  but shall not be  obligated  to,  direct the Trustee to establish a record
date for the purpose of determining  the Persons  entitled to (i) waive any past
default with respect to the  Securities  in accordance  with Section 4.10,  (ii)
consent to any  supplemental  indenture in accordance  with Section 7.2 or (iii)
waive compliance with any term, condition or provision of any covenant hereunder
(if the Indenture should expressly provide for such waiver). If a record date is
fixed,  the Holders of Securities on such record date, or their duly  designated
proxies, and any such Persons, shall be entitled to waive any such past default,
consent to any such  supplemental  indenture or waive  compliance  with any such
term, condition or provision,  whether or not such Holder remains a Holder after
such  record  date;  provided,  however,  that  unless such waiver or consent is
obtained  from  the  Holders,  or  duly  designated  proxies,  of the  requisite
principal amount of Outstanding

                                      -52-

<PAGE>

Securities  prior to the date which is the 90th day after such record date,  any
such waiver or consent previously given shall  automatically and without further
action by any Holder be cancelled and of no further effect.

                                  ARTICLE SEVEN

                             SUPPLEMENTAL INDENTURES

                  SECTION  7.1  Supplemental   Indentures   Without  Consent  of
Securityholders.  The Issuer,  when  authorized  by a resolution of its Board of
Directors,  and the  Trustee may from time to time and at any time enter into an
indenture  or  indentures  supplemental  hereto  (which  shall  conform  to  the
provisions of the TIA as in force at the date of the execution  thereof) for one
or more of the following purposes:

                  (a) to convey,  transfer,  assign,  mortgage  or pledge to the
         Trustee as security for the Securities any property or assets;

                  (b) to evidence the  succession of another  corporation to the
         Issuer, or successive successions,  and the assumption by the successor
         corporation of the covenants,  agreements and obligations of the Issuer
         pursuant to Article Eight;

                  (c) to  add  to the  covenants  of  the  Issuer  such  further
         covenants,  restrictions,  conditions or provisions  (including without
         limitation  provisions necessary or desirable to qualify this Indenture
         under the TIA) as its Board of Directors and the Trustee shall consider
         to be for the protection or benefit of the Holders of  Securities,  and
         to make the occurrence, or the occurrence and continuance, of a default
         in  any  such  additional   covenants,   restrictions,   conditions  or
         provisions an Event of Default permitting the enforcement of all or any
         of the several remedies provided in this Indenture as herein set forth;
         provided that in respect of any such additional

                                      -53-

<PAGE>

         covenant,   restriction,   condition  or  provision  such  supplemental
         indenture  may provide for a particular  period of grace after  default
         (which period may be shorter or longer than that allowed in the case of
         other defaults) or may provide for an immediate  enforcement  upon such
         an Event of Default or may limit the remedies  available to the Trustee
         upon such an Event of Default or may limit the right of the  Holders of
         a majority in aggregate  principal  amount of the  Securities  to waive
         such an Event of Default;

                  (d) to cure any  ambiguity  or to  correct or  supplement  any
         provision  contained herein or in any supplemental  indenture which may
         be defective or inconsistent with any other provision  contained herein
         or in any  supplemental  indenture  or to make such other  provision in
         regard to matters or questions  arising  under this  Indenture or under
         any supplemental indenture as the Board of Directors may deem necessary
         or desirable,  provided that no such action shall adversely  affect the
         interests of the Holders of the Securities;

                  (e) to provide for adjustment of conversion rights pursuant to
         Section 12.5; or

                  (f) to evidence the removal or  resignation of the Trustee and
         the appointment of a successor  Trustee or Trustees pursuant to Article
         Five.

                  The Trustee is hereby  authorized  to join in the execution of
any such supplemental  indenture, to make any further appropriate agreements and
stipulations,  which may be therein  contained,  and to accept  the  conveyance,
transfer,  assignment,  mortgage or pledge of any property  thereunder,  but the
Trustee  shall not be  obligated to enter into any such  supplemental  indenture
which  affects  adversely  the  Trustee's  own  rights,  duties,  immunities  or
liabilities under this Indenture or otherwise.

                  Any  supplemental  indenture  authorized by the  provisions of
this Section 7.1 may be executed without the

                                      -54-

<PAGE>

consent  of  the  Holders  of any of the  Securities  at the  time  Outstanding,
notwithstanding any of the provisions of Section 7.2.

                  SECTION   7.2   Supplemental   Indentures   with   Consent  of
Securityholders.  With the consent (evidenced as provided in Article Six) of the
Holders  of not less  than a  majority  in  aggregate  principal  amount  of the
Securities at the time Outstanding,  the Issuer, when authorized by a resolution
of its Board of  Directors,  and the Trustee  may,  from time to time and at any
time,  enter into an indenture or  indentures  supplemental  hereto (which shall
conform  to the  provisions  of the TIA as in  force  at the  date of  execution
thereof) for the purpose of adding any  provisions  to or changing in any manner
or eliminating  any of the  provisions of this Indenture or of any  supplemental
indenture  or of  modifying  in any  manner  the  rights of the  Holders  of the
Securities;  provided that no such  supplemental  indenture shall (a) extend the
final  maturity  of any  Security,  or reduce the  principal  amount  thereof or
premium,  if any,  thereon,  or reduce the rate or extend the time of payment of
interest thereon,  or any premium payable upon the redemption thereof, or change
the place of payment  where,  or the coin or currency in which,  any  principal,
premium or interest is payable,  or reduce or alter the method of calculation of
any amount payable on redemption,  repurchase or repayment  thereof (or the time
at which any such redemption, repurchase or repayment may be made), or impair or
adversely  affect  the right of any  Securityholder  to  institute  suit for the
payment or  conversion  thereof  or  adversely  affect the right to convert  the
Securities in accordance with Article Twelve, in each case,  without the consent
of the Holder of each Security so affected; provided no consent of any Holder of
any Security shall be necessary under this Section 7.2 to permit the Trustee and
the Issuer to execute  supplemental  indentures  pursuant to Section  7.1(e) and
Section  12.5 of this  Indenture;  or (b) reduce  the  aforesaid  percentage  in
principal amount of Outstanding Securities,  the consent of the Holders of which
is  required  for any such  supplemental  indenture,  without the consent of the
Holders of each Security so affected; or (c) reduce the percentage of Securities
necessary to consent to waive any past default

                                      -55-

<PAGE>

under this Indenture to less than a majority, without the consent of the Holders
of each  Security  so  affected;  or (d)  modify any of the  provisions  of this
Section or Section  4.10,  except to increase  any such  percentage  provided in
either  such  Section  or to  provide  that  certain  other  provisions  of this
Indenture cannot be modified or waived without the consent of the Holder of each
Security affected thereby.

                  Upon the  request of the  Issuer,  accompanied  by a copy of a
resolution of the Board of Directors (which resolution may provide general terms
or  parameters  for such action and may provide that the specific  terms of such
action may be  determined in  accordance  with or pursuant to an Issuer  Order),
certified by the Secretary or an Assistant Secretary of the Issuer,  authorizing
the execution of any such supplemental  indenture,  and upon the filing with the
Trustee of evidence of the consent of  Securityholders  and other documents,  if
any,  required by Section  6.1,  the  Trustee  shall join with the Issuer in the
execution of such  supplemental  indenture  unless such  supplemental  indenture
adversely  affects the Trustee' own rights,  duties,  immunities or  liabilities
under  this  Indenture  or  otherwise,  in  which  case the  Trustee  may in its
discretion,  but  shall  not be  obligated  to,  enter  into  such  supplemental
indenture.

                  It  shall   not  be   necessary   for  the   consent   of  the
Securityholders  under  this  Section  to  approve  the  particular  form of any
proposed  supplemental  indenture,  but it shall be  sufficient  if such consent
shall approve the substance thereof.

                  Promptly  after the execution by the Issuer and the Trustee of
any  supplemental  indenture  pursuant to the  provisions of this  Section,  the
Issuer  shall  mail a notice  thereof  by  first-class  mail to the  Holders  of
Securities at their  addresses as they shall appear on the registry books of the
Issuer,  setting  forth in  general  terms the  substance  of such  supplemental
indenture. Any failure of the Issuer to mail such notice, or any defect therein,
shall  not,  however,  in any way  impair or  affect  the  validity  of any such
supplemental indenture.

                                      -56-

<PAGE>

                  SECTION  7.3  Effect  of  Supplemental  Indenture.   Upon  the
execution of any supplemental  indenture pursuant to the provisions hereof, this
Indenture  shall be and be deemed  to be  modified  and  amended  in  accordance
therewith and the respective rights, limitations of rights, obligations,  duties
and immunities  under this Indenture of the Trustee,  the Issuer and the Holders
of Securities shall thereafter be determined,  exercised and enforced  hereunder
subject in all respects to such modifications and amendments,  and all the terms
and conditions of any such  supplemental  indenture shall be and be deemed to be
part of the terms and conditions of this Indenture for any and all purposes.

                  SECTION 7.4  Documents  to Be Given to Trustee.  The  Trustee,
subject to the  provisions of Sections 5.1 and 5.2, may upon request  receive an
Officers'  Certificate and an Opinion of Counsel as conclusive evidence that any
such  supplemental  indenture  complies with the  applicable  provisions of this
Indenture.

                  SECTION 7.5 Notation on Securities in Respect of  Supplemental
Indentures.  Securities  authenticated  and delivered after the execution of any
supplemental  indenture  pursuant to the  provisions  of this Article may bear a
notation as to any matter provided for by such  supplemental  indenture.  If the
Issuer shall so  determine,  new  Securities  so modified as to conform,  in the
opinion  of the  Board  of  Directors,  to any  modification  of this  Indenture
contained  in any such  supplemental  indenture  may be  prepared by the Issuer,
authenticated  by the Trustee and delivered in exchange for the Securities  then
Outstanding.

                                  ARTICLE EIGHT

                    CONSOLIDATION, MERGER, SALE OR CONVEYANCE

                  SECTION 8.1 Covenant Not to Merge, Consolidate, Sell or Convey
Property  Except Under Certain  Conditions.  The Issuer may not  consolidate  or
merge with or into (whether or not the Issuer is the Surviving Person), or sell,
assign, transfer, lease, convey or otherwise dispose of all or

                                      -57-

<PAGE>

substantially   all  of  its  properties  or  assets  in  one  or  more  related
transactions, to another Person (each a "Disposition"), unless:

         (i) the Surviving  Person is a corporation  organized or existing under
         the laws of the United  States,  any state  thereof or the  District of
         Columbia;

         (ii) the  Surviving  Person (if other than the Issuer)  assumes all the
         obligations of the Issuer under the Securities and this Indenture,  and
         makes provision for conversion  rights in accordance with Section 12.5,
         pursuant to a supplemental indenture in a form reasonably  satisfactory
         to the Trustee; and

         (iii) immediately after such Disposition,  no Event of Default or event
         that,  after the giving of notice or the passage of time or both, would
         be an Event of Default, shall have occurred and be continuing.

                  SECTION 8.2 Successor  Corporation or Entity  Substituted.  In
case of any such consolidation,  merger, sale or conveyance,  and following such
an assumption by the successor  corporation,  partnership  or limited  liability
company,  such successor  corporation,  partnership or limited liability company
shall succeed to and be substituted  for the Issuer,  with the same effect as if
it had been named herein.

                  Such successor  corporation,  partnership or limited liability
company may cause to be signed,  and may issue  either in its own name or in the
name  of the  Issuer  prior  to  such  succession  any or all of the  Securities
issuable  hereunder which  theretofore  shall not have been signed by the Issuer
and delivered to the Trustee; and, upon the order of such successor corporation,
partnership or limited liability company,  instead of the Issuer, and subject to
all the terms,  conditions and  limitations in this  Indenture  prescribed,  the
Trustee shall authenticate and shall deliver

                                      -58-

<PAGE>

any  Securities  which  previously  shall have been signed and  delivered by the
officers  of the Issuer to the Trustee for  authentication,  and any  Securities
which such  successor  corporation,  partnership  or limited  liability  company
thereafter  shall  cause to be signed  and  delivered  to the  Trustee  for that
purpose.  All of the  Securities  so issued shall in all respects  have the same
legal rank and benefit under this  Indenture as the  Securities  theretofore  or
thereafter  issued in accordance  with the terms of this Indenture as though all
of such Securities had been issued at the date of the execution hereof.

                  In case of any  such  consolidation,  merger,  sale,  lease or
conveyance,  such changes in phraseology  and form (but not in substance) may be
made in the Securities thereafter to be issued as may be appropriate.

                  In the  event of any such  sale or  conveyance  (other  than a
conveyance  by  way  of  lease),  the  Issuer  or  any  successor   corporation,
partnership or limited  liability  company which shall  theretofore  have become
such in the  manner  described  in this  Article  shall be  discharged  from all
obligations  and covenants  under this  Indenture and the  Securities and may be
liquidated and dissolved.

                  SECTION 8.3 Opinion of Counsel and  Officers'  Certificate  to
Trustee.  The Trustee,  subject to the  provisions  of Sections 5.1 and 5.2, may
upon request  receive an Opinion of Counsel  prepared in accordance with Section
10.5 and an Officers' Certificate (confirming  satisfaction of the conditions of
clauses (i), (ii) and (iii) of Section 8.1) as conclusive evidence that any such
consolidation,  merger, sale, lease or conveyance,  and any such assumption, and
any such liquidation or dissolution,  complies with the applicable provisions of
this Indenture.

                                      -59-

<PAGE>

                                  ARTICLE NINE

                           SATISFACTION AND DISCHARGE
                         OF INDENTURE; UNCLAIMED MONEYS

                  SECTION 9.1 Satisfaction and Discharge of Indenture. If at any
time (a) the Issuer  shall have paid or caused to be paid the  principal  of and
premium, if any, and interest on all the Securities then Outstanding  hereunder,
as and when the same shall have become due and payable,  or (b) the Issuer shall
have  delivered  to the  Trustee for  cancellation  all  Securities  theretofore
authenticated  (other than any Securities which shall have been destroyed,  lost
or stolen and which shall have been replaced or paid as provided in Section 2.7)
or (c) (i) all such  Securities  not  theretofore  delivered  to the Trustee for
cancellation (x) shall have become due and payable, or (y) are by their terms to
become due and payable within one year or are to be called for redemption within
one year under  arrangements  reasonably  satisfactory  to the  Trustee  for the
giving of notice of  redemption,  and (ii) the  Issuer  shall  have  irrevocably
deposited or caused to be  deposited  with the Trustee as trust funds the entire
amount in cash (other than moneys  repaid by the Trustee or any Paying  Agent to
the  Issuer in  accordance  with  Section  9.4) or U.S.  Government  Obligations
maturing as to principal  and interest at such times and in such amounts as will
insure the  availability  of cash, or a combination  thereof,  sufficient in the
opinion  of a  nationally  recognized  firm of  independent  public  accountants
expressed in a written  certification  thereof delivered to the Trustee,  to pay
the principal of and interest on all Securities on each date that such principal
or interest is due and payable;  and if, in any such case, the Issuer shall also
pay or cause to be paid all other sums  payable  hereunder  by the Issuer,  then
this  Indenture  shall cease to be of further effect (except as to (i) rights of
registration  of  transfer,  conversion  and  exchange  of  Securities,  and the
Issuer's right of optional  redemption  contemplated  in clause  (c)(i)(y) above
(but not  otherwise  and not  including  the  Holders'  right of  redemption  or
repurchase   contemplated  by  Article  Thirteen  or  Article  Fourteen),   (ii)
substitution of apparently mutilated,

                                      -60-

<PAGE>

defaced,  destroyed,  lost or stolen Securities,  (iii) rights of the Holders of
Securities  to receive  payments of principal  thereof and  premium,  if any and
interest  thereon  upon the  original  stated due dates  therefor  (but not upon
acceleration),  (iv) the  rights,  obligations  and  immunities  of the  Trustee
hereunder, including any right to compensation and indemnification under Section
5.5, and (v) the rights of the Holders of  Securities  as  beneficiaries  hereof
with respect to the property so deposited with the Trustee payable to all or any
of  them),  and  the  Trustee,  on  Issuer  Order  accompanied  by an  Officers'
Certificate  and an Opinion  of  Counsel  stating  that the  provisions  of this
Section have been complied with and at the cost and expense of the Issuer, shall
execute  proper   instruments   prepared  by  the  Issuer   acknowledging   such
satisfaction of and discharging  this  Indenture,  provided,  that the rights of
Holders of the  Securities  to receive  amounts  in  respect  of  principal  of,
premium,  if any,  and  interest  on the  Securities  held by them  shall not be
delayed longer than required by  then-applicable  mandatory rules or policies of
any securities  exchange upon which the Securities are listed.  In addition,  in
connection  with the  satisfaction  and discharge  pursuant to clause  (c)(i)(y)
above,  the  Trustee  shall give  notice to the  Holders of  Securities  of such
satisfaction  and discharge.  The Issuer agrees to reimburse the Trustee for any
costs or expenses thereafter  reasonably and properly incurred and to compensate
the Trustee for any services thereafter  reasonably and properly rendered by the
Trustee in connection with this Indenture or the Securities.

                  Notwithstanding   the   satisfaction  and  discharge  of  this
Indenture,  the obligations of the Issuer to the Trustee under Section 5.5 shall
survive.

                  SECTION  9.2  Application  by Trustee of Funds  Deposited  for
Payment  of  Securities.  Subject  to Section  9.4,  all  moneys and  securities
deposited  with the  Trustee  pursuant to Section 9.1 shall be held in trust and
applied  by it to the  payment,  either  directly  or through  any Paying  Agent
(including  the Issuer  acting as its own Paying  Agent),  to the Holders of the
particular Securities for the

                                      -61-

<PAGE>

payment or  redemption of which such moneys or  Securities  have been  deposited
with the  Trustee of all sums due and to become due thereon  for  principal  and
interest;  but such moneys or securities need not be segregated from other funds
except to the extent required by law.

                  SECTION  9.3  Repayment  of Moneys  Held by Paying  Agent.  In
connection with the satisfaction and discharge of this Indenture with respect to
Securities,  all moneys then held by any Paying  Agent under the  provisions  of
this Indenture shall,  upon Issuer Order, be repaid to it or paid to the Trustee
and  thereupon  such Paying Agent shall be released  from all further  liability
with respect to such moneys.

                  SECTION 9.4 Return of Moneys Held by Trustee and Paying  Agent
Unclaimed for Two Years. Any moneys deposited with or paid to the Trustee or any
Paying Agent for the payment of the principal of or premium, if any, or interest
on any Security and not applied but remaining  unclaimed for two years after the
date upon which such  principal,  premium or interest  shall have become due and
payable  shall,  upon the  written  request of the  Issuer and unless  otherwise
required by mandatory provisions of applicable escheat or abandoned or unclaimed
property law, be repaid to the Issuer by the Trustee or such Paying  Agent,  and
the Holder of the  Securities  shall,  unless  otherwise  required by  mandatory
provisions  of  applicable  escheat or  abandoned or  unclaimed  property  laws,
thereafter  look only to the Issuer  for any  payment  which such  Holder may be
entitled to collect,  and all  liability of the Trustee or any Paying Agent with
respect to such  moneys  shall  thereupon  cease;  provided,  however,  that the
Trustee or such Paying Agent,  before being  required to make any such repayment
with respect to moneys deposited with it for any payment,  shall, at the expense
of the Issuer,  mail by first-class  mail to Holders of such Securities at their
addresses as they shall appear on the Security  register notice that such moneys
remain and that, after a date specified therein, which shall not be less than 30
days from the date of such  mailing,  any  unclaimed  balance of such money then
remaining will be repaid to the Issuer upon Issuer Order.

                                      -62-

<PAGE>

                  SECTION 9.5 Indemnity  for U.S.  Government  Obligations.  The
Issuer shall pay and indemnify the Trustee  against any tax, fee or other charge
imposed  on or  assessed  against  the  U.S.  Government  Obligations  deposited
pursuant to Section 9.1 or the principal or interest received in respect of such
obligations.

                                   ARTICLE TEN

                            MISCELLANEOUS PROVISIONS

                  SECTION 10.1 Partners, Incorporators,  Stockholders,  Officers
and Directors of Issue Exempt from  Individual  Liability.  No recourse under or
upon any obliga tion, covenant or agreement  contained in this Indenture,  or in
any Security,  or because of any indebtedness  evidenced  thereby,  shall be had
against  any  incorporator,  as such,  or  against  any past,  present or future
stockholder,  officer or director,  as such,  of the Issuer or of any partner or
member of the Issuer or of any successor,  either directly or through the Issuer
or any successor,  under any rule of law, statute or constitutional provision or
by the enforcement of any assessment or by any legal or equitable  proceeding or
otherwise,  all such  liability  being  expressly  waived  and  released  by the
acceptance  of the  Securities  by  the  Holders  thereof  and  as  part  of the
consideration for the issue of the Securities.

                  SECTION 10.2  Provisions  of Indenture for the Sole Benefit of
Parties and  Securityholders.  Nothing in this  Indenture or in the  Securities,
expressed or implied,  shall give or be  construed to give to any Person,  other
than the parties hereto and their  successors and the Holders of the Securities,
any legal or equitable right,  remedy or claim under this Indenture or under any
covenant or provision herein contained,  all such covenants and provisions being
for the sole benefit of the parties hereto and their  successors and the Holders
of the Securities.

                  SECTION  10.3  Successors  and  Assigns  of  Issuer  Bound  by
Indenture. All the covenants, stipulations,

                                      -63-

<PAGE>

promises  and  agreements  in this  Indenture  contained  by or on behalf of the
Issuer shall bind its successors and assigns, whether so expressed or not.

                  SECTION  10.4  Notices  and  Demands  on Issuer,  Trustee  and
Securityholders.  Any notice or demand which by any provision of this  Indenture
is required or  permitted to be given or served by the Trustee or by the Holders
of  Securities  to or on the  Issuer  may be given or served by being  deposited
postage  prepaid,  first-class mail (except as otherwise  specifically  provided
herein)  addressed  (until another  address of the Issuer is filed by the Issuer
with the Trustee) to American Tower Corporation,  116 Huntington Avenue, Boston,
MA  02116,  Attention:  Chief  Financial  Officer  and  Secretary.  Any  notice,
direction,  request or demand by the Issuer or any Securityholder to or upon the
Trustee  shall be  deemed  to have  been  sufficiently  given  or made,  for all
purposes, if given or made at the Corporate Trust Office,  Attention:  Corporate
Trust Trustee Administration Department.

                  Where this  Indenture  provides  for notice to  Holders,  such
notice shall be sufficiently  given (except as otherwise  specifically  provided
herein) if in writing,  and mailed,  first-class postage prepaid, to each Holder
entitled thereto, at his last address as it appears in the Security register. In
any case where  notice to Holders is given by mail,  neither the failure to mail
such notice,  nor any defect in any notice so mailed,  to any particular  Holder
shall affect the sufficiency of such notice with respect to other Holders. Where
this Indenture  provides for notice in any manner,  such notice may be waived in
writing by the Person  entitled to receive such notice,  either  before or after
the event,  and such waiver shall be the  equivalent of such notice.  Waivers of
notice by Holders shall be filed with the Trustee,  but such filing shall not be
a condition  precedent to the validity of any action taken in reliance upon such
waiver.

                  In case, by reason of the suspension of or irregu  larities in
regular mail service, it shall be impracticable to mail notice to the Issuer and
Securityholders when such

                                      -64-

<PAGE>

notice is required to be given pursuant to any provision of this Indenture, then
any manner of giving such notice as shall be  satisfactory  to the Trustee shall
be deemed to be a sufficient giving of such notice.

                  SECTION 10.5 Officers'  Certificates  and Opinions of Counsel;
Statements to Be Contained Therein. Upon any application or demand by the Issuer
to the Trustee to take any action under any of the provisions of this Indenture,
the Issuer shall  furnish to the Trustee an Officers'  Certificate  stating that
all conditions precedent provided for in this Indenture relating to the proposed
action have been  complied  with and an Opinion of Counsel  stating  that in the
opinion of such counsel all such  conditions  precedent have been complied with,
except  that in the case of any  such  application  or  demand  as to which  the
furnishing of such documents is  specifically  required by any provision of this
Indenture  relating to such  particular  application  or demand,  no  additional
certificate or opinion need be furnished.

                  Each certificate or opinion provided for in this Indenture and
delivered to the Trustee with respect to compliance with a condition or covenant
provided for in this  Indenture  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 the  statements or opinions  contained in such  certificate  or opinion are
based,  (c) a statement  that,  in the opinion of such person,  he has made such
examination  or  investigation  as is  necessary  to enable  him to  express  an
informed  opinion as to  whether  or not such  covenant  or  condition  has been
complied  with, and (d) a statement as to whether or not, in the opinion of such
person, such condition or covenant has been complied with.

                  Any  certificate,  statement  or  opinion of an officer of the
Issuer may be based, insofar as it relates to legal matters,  upon a certificate
or opinion of or represen tations by counsel, unless such officer knows that the
certificate or opinion or representations with respect to the matters upon which
his  certificate,  statement or opinion may be based as aforesaid are erroneous,
or in the exercise

                                      -65-

<PAGE>

of reasonable  care should know that the same are  erroneous.  Any  certificate,
statement  or opinion of counsel may be based,  insofar as it relates to factual
matters,  information  with respect to which is in the possession of the Issuer,
upon the certificate,  statement or opinion of or representa tions by an officer
or officers  of the Issuer,  unless  such  counsel  knows that the  certificate,
statement or opinion or  representations  with respect to the matters upon which
his  certificate,  statement or opinion may be based as aforesaid are erroneous,
or in the exercise of reasonable care should know that the same are erroneous.

                  Any  certificate,  statement  or  opinion of an officer of the
Issuer or of counsel may be based,  insofar as it relates to accounting matters,
upon a certificate or opinion of or  representations by an accountant or firm of
accountants in the employ of the Issuer,  unless such officer or counsel, as the
case may be,  knows that the  certificate  or opinion  or  representations  with
respect to the  accounting  matters  upon which his  certificate,  statement  or
opinion  may  be  based  as  aforesaid  are  erroneous,  or in the  exercise  of
reasonable care should know that the same are erroneous.

                  Any certificate or opinion of any  independent  firm of public
accountants  filed with the Trustee shall contain a statement  that such firm is
independent.

                  SECTION  10.6  Payments  Due on  Saturdays,  Sundays and Legal
Holidays.  If the date of maturity of interest on or principal of the Securities
or the date fixed for redemp tion or  repayment of any Security or the last date
on which a Holder of Securities has a right to convert his Securities  shall not
be a Business Day, then  (notwithstanding  any other provision of this Indenture
or of the  Securities)  payment of interest or  principal or  conversion  of the
Securities need not be made on such date, but may be made on the next succeeding
Business  Day with the same force and effect as if made on the date of  maturity
or the  date  fixed  for  redemption  or  repayment  or on  such  last  day  for
conversion, and no interest shall accrue for the period after such date.

                                      -66-

<PAGE>

                  SECTION 10.7 Conflict with TIA. Whether or not qualified under
the TIA,  this  Indenture  shall be  interpreted  as though it were so qualified
including provisions required by the TIA or provisions deemed included except as
varied by this Indenture. If any provision hereof limits, qualifies or conflicts
with a provision  of the TIA that is required  under the TIA to be a part of and
govern this Indenture,  the latter provision shall control.  If any provision of
this  Indenture  modifies or excludes  any  provision  of the TIA that may be so
modified  or  excluded,  the latter  provision  shall be deemed to apply to this
Indenture as so modified or to be excluded, as the case may be.

                  SECTION 10.8  Communications  by Holders  with Other  Holders.
Securityholders may communicate pursuant to Section 312(b) of the TIA with other
Holders with respect to their rights under this Indenture or the Securities. The
Issuer,  the  Trustee,  the  Registrar  and any  other  person  shall  have  the
protection of Section 312(c) of the TIA.

                  SECTION 10.9 Issuer to Furnish  Trustee Names and Addresses of
Holders. The Issuer will furnish or cause to be furnished to the Trustee:

                  (a)  semiannually,  not later  than  January 15 and July 15 in
         each year, a list, in such form as the Trustee may reasonably  require,
         of the names and addresses of the Securityholders as of a date not more
         than 15 days prior to the delivery thereof, and

                  (b) at such other times as the Trustee may request in writing,
         within 30 days after the receipt by the Issuer of any such  request,  a
         list of  similar  form and  content  as of a date not more than 15 days
         prior to the time such list is furnished;

excluding from any such list names and addresses  received by the Trustee in the
capacity of Registrar.

                  SECTION 10.10 New York Law to Govern.  This Indenture and each
Security  shall be  deemed to be a  contract  under the laws of the State of New
York, and for all

                                      -67-

<PAGE>

purposes shall be construed in accordance  with the laws of said State,  without
regard to principles of conflicts of laws.

                  SECTION 10.11 Counterparts.  This Indenture may be executed in
any  number  of  counterparts,  each of  which  shall be an  original;  but such
counterparts shall together constitute but one and the same instrument.

                  SECTION  10.12  Effect of  Headings.  The  Article and Section
headings herein and the Table of Contents are for convenience only and shall not
affect the construction hereof.

                                 ARTICLE ELEVEN

                            REDEMPTION OF SECURITIES

                  SECTION 11.1 Right of Optional Redemption;  Prices. The Issuer
at its option may, on and after  February 20, 2003,  redeem all, or from time to
time any part of, the Securities upon payment of the optional  Redemption Prices
set forth in the form of Security  attached as Exhibit A hereto,  together  with
accrued interest to the date fixed for redemption.

                  SECTION 11.2 Notice of Redemption; Partial Redemptions. Notice
of  redemption to the Holders of Securities to be redeemed as a whole or in part
shall be given by mailing notice of such redemption by first-class mail, postage
prepaid,  at least 20 days and not more than 60 days prior to the date fixed for
redemption to such Holders of  Securities at their last  addresses as they shall
appear upon the registry books.  Any notice which is mailed in the manner herein
provided shall be conclusively  presumed to have been duly given, whether or not
the Holder receives the notice. Failure to give notice by mail, or any defect in
the notice to the Holder of any Security designated for redemption as a whole or
in part,  shall not affect the validity of the proceedings for the redemption of
any other Security.

                                      -68-

<PAGE>

                  The notice of redemption to each such Holder shall specify the
principal  amount of each Security held by such Holder to be redeemed,  the date
fixed for redemption (the "Redemption Date"), the CUSIP numbers,  the applicable
Redemption Price, the place or places of payment, that payment will be made upon
presentation and surrender of such Securities, that interest accrued to the date
fixed for  redemption  will be paid as  specified in said notice and that on and
after said date interest  thereon or on the portions thereof to be redeemed will
cease to accrue,  and shall also specify the Conversion Price then in effect and
the date on which the right to convert such  Securities or the portions  thereof
to be redeemed will expire.  In case any Security is to be redeemed in part only
the notice of redemption shall state the portion of the principal amount thereof
to be redeemed and shall state that on and after the date fixed for  redemption,
upon  surrender  of such  Security,  a new Security or  Securities  in principal
amount equal to the unredeemed portion thereof will be issued.

                  The notice of  redemption  of Securities to be redeemed at the
option of the Issuer shall be given by the Issuer or, at the  Issuer's  request,
by the Trustee in the name and at the expense of the Issuer.

                  At  least  one  Business  Day  prior  to the  Redemption  Date
specified in the notice of  redemption  given as provided in this  Section,  the
Issuer will deposit  with the Trustee or with one or more Paying  Agents (or, if
the Issuer is acting as its own Paying Agent,  set aside,  segregate and hold in
trust as  provided  in Section  2.3) an amount of money suffi cient to redeem on
the  Redemption  Date all the  Securities so called for  redemption  (other than
those theretofore  surrendered for conversion pursuant to Article Twelve) at the
appropriate  Redemption  Price,  together with accrued interest to and including
the date  fixed  for  redemption.  If any  Security  called  for  redemption  is
converted  pursuant  hereto,  any money deposited with the Trustee or any Paying
Agent or so  segregated  and held in trust for the  redemption  of such Security
shall be paid to the Issuer upon Issuer  Order,  or, if then held by the Issuer,
shall be discharged from such trust. If less than all the outstanding Securi-

                                      -69-
<PAGE>

ties are to be redeemed, the Issuer will deliver to the Trustee at least 10 days
prior to the date of making of the notice of redemption an Officers' Certificate
stating the aggregate principal amount of Securities to be redeemed.

                  If  less  than  all the  Securities  are to be  redeemed,  the
Trustee shall select,  by lot, pro rata or by such other manner as it shall deem
appropriate and fair,  Securities to be redeemed in whole or in part. Securities
may  be  redeemed  in  part  in  multiples  equal  to  the  minimum   authorized
denomination for Securities or any multiple thereof.  The Trustee shall promptly
notify the Issuer in writing of the Securities  selected for redemption  and, in
the case of any Securities selected for partial redemption, the principal amount
thereof to be redeemed.  For all purposes of this Indenture,  unless the context
otherwise  requires,  all  provisions  relating to the  redemption of Securities
shall  relate,  in the case of any Security  redeemed or to be redeemed  only in
part, to the portion of the principal  amount of such Security which has been or
is  to  be  redeemed.  If  any  Security  selected  for  partial  redemption  is
surrendered for conversion after such selection,  the converted  portion of such
Security  shall be  deemed  (so far as may be) to be the  portion  selected  for
redemption. Upon any redemption of less than all the Securities, for purposes of
the  selection  for  redemption,  the  Issuer  and  the  Trustee  may  treat  as
Outstanding  Securities  surrendered for conversion during the period of 15 days
next  preceding  the  mailing of a notice of  redemption,  and need not treat as
Outstanding  any  Security  authenticated  and  delivered  during such period in
exchange for the  unconverted  portion of any Security  converted in part during
such period.

                  SECTION 11.3 Payment of Securities  Called for Redemption.  If
notice  of  redemption  has been  given as above  provided,  the  Securities  or
portions of Securities  specified in such notice shall become due and payable on
the date and at the place  stated in such  notice at the  applicable  Redemption
Price,  together  with  interest  accrued  to and  including  the date fixed for
redemption,  and on and after said date (unless the Issuer shall  default in the
payment of

                                      -70-

<PAGE>

such Securities at the Redemption Price,  together with interest accrued to said
date)  interest  on the  Securities  or  portions  of  Securities  so called for
redemption  shall cease to accrue and such Securities shall cease from and after
the close of business on the  Business Day  immediately  prior to the date fixed
for  redemption to be  convertible  pursuant to the provisions of Article Twelve
or,  except as provided  in Sections  2.4 and 9.4, be entitled to any benefit or
security under this  Indenture,  and the Holders  thereof shall have no right in
respect of such Securities except the right to receive the applicable Redemption
Price  thereof  and  unpaid  interest  to  and  including  the  date  fixed  for
redemption.  On  presentation  and  surrender of such  Securities  at a place of
payment  specified in said notice,  said  Securities or the  specified  portions
thereof  shall be paid and redeemed by the Issuer at the  applicable  Redemption
Price,  together with interest  accrued  thereon to and including the date fixed
for redemption,  provided that any payment of interest  becoming due on or prior
to the date  fixed  for  redemption  shall be  payable  to the  Holders  of such
Securities  registered as such on the relevant  record date subject to the terms
and provisions of Section 2.11 hereof.

                  If any  Security  called for  redemption  shall not be so paid
upon surrender thereof for redemption,  the principal shall,  until paid or duly
provided for,  bear  interest from the date fixed for  redemption at the rate of
interest  specified in such Security and such Security shall remain  convertible
pursuant  to the  provisions  of  Article  Twelve  until the  principal  of such
Security shall have been paid or duly provided for.

                  Upon  presentation of any Security  redeemed in part only, the
Issuer shall execute and the Trustee shall authenticate and deliver to or on the
order of the Holder  thereof,  at the expense of the Issuer,  a new  Security or
Securities,  of  authorized  denominations,  in  principal  amount  equal to the
unredeemed portion of the Security so presented.

                  SECTION 11.4 Exclusion of Certain  Securities from Eligibility
for Selection for Redemption. Securities shall

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<PAGE>

be excluded from eligibility for selection for redemption if they are identified
by  registration  and  certificate  number in a written  statement  signed by an
Officer of the Issuer and delivered to the Trustee at least 40 days prior to the
last date on which  notice of  redemption  may be given as being owned of record
and beneficially by, and not pledged or hypothecated by either (a) the Issuer or
(b) an entity specifically  identified in such Officers' Certificate directly or
indirectly  controlling  or  controlled  by or under  direct or indirect  common
control with the Issuer.

                  SECTION 11.5 Conversion Arrangement on Call for Redemption. In
connection with any redemption of the Securities, the Issuer may arrange for the
purchase and  conversion  of any  Securities  by an  agreement  with one or more
investment  bankers or other  purchasers  (the  "Purchasers")  to purchase  such
Securities by paying to the Trustee in trust for the Holders, on or before 11:00
a.m., Eastern Standard Time, on the Redemption Date, an amount not less than the
applicable  Redemption  Price,  together with interest accrued and unpaid to the
Redemption  Date, of such Securities.  Notwithstanding  anything to the contrary
contained in this Article,  the  obligation of the Issuer to pay the  Redemption
Price,  together with interest  accrued and unpaid to the Redemption Date, shall
be deemed to be satisfied and discharged to the extent such amount is so paid by
such Purchasers.  If such an agreement is entered into (a copy of which shall be
filed with the Trustee prior to the close of business on the second Business Day
immediately  prior to the Redemption Date), any Securities called for redemption
that are not duly  surrendered for conversion by the Holders thereof may, at the
option of the Issuer,  be deemed,  to the fullest  extent  permitted by law, and
consistent with any agreement or agreements with such Purchasers, to be acquired
by such  Purchasers  from such  Holders  and  (notwithstanding  anything  to the
contrary  contained  in  this  Article)   surrendered  by  such  Purchasers  for
conversion,  all  as of  immediately  prior  to the  close  of  business  on the
Redemption Date (and the right to convert any such Securities  shall be extended
through such time), subject to payment of the above amount as aforesaid.  At the
written direction of the Issuer, the Trustee shall hold and

                                      -72-

<PAGE>

dispose of any such  amount paid to it by the  Purchasers  to the Holders in the
same  manner  as it  would  monies  deposited  with  it by the  Issuer  for  the
redemption of  Securities.  Without the  Trustee's  prior  written  consent,  no
arrangement  between  the  Issuer  and  such  Purchasers  for the  purchase  and
conversion  of any  Securities  shall  increase or  otherwise  affect any of the
powers,  duties,  responsibilities or obligations of the Trustee as set forth in
this Indenture, and the Issuer agrees to indemnify the Trustee from, and hold it
harmless against, any loss, liability or expense arising out of or in connection
with any such  arrangement  for the purchase and  conversion  of any  Securities
between  the  Issuer  and such  Purchasers,  including  the costs and  expenses,
including  reasonable legal fees,  incurred by the Trustee in the defense of any
claim  or  liability  arising  out of or in  connection  with  the  exercise  or
performance of any of its powers, duties,  responsibilities or obligations under
this Indenture.

                                 ARTICLE TWELVE

                            CONVERSION OF SECURITIES

                  SECTION 12.1 Conversion Privilege.  A Holder of a Security may
convert it into Class A Common Stock of the Issuer at any time prior to maturity
at the  conversion  price  then in  effect,  except  that,  with  respect to any
Security  called for redemption,  such  conversion  right shall terminate at the
close of business on the Business Day immediately preceding the Redemption Date,
Change in Control  Repurchase  Date or Repurchase  Date (unless the Issuer shall
default in making the  redemption or repurchase  payment then due, in which case
the conversion  right shall  terminate on the date such default is cured and, if
applicable,  the  provisions of Section  13.2(d) are  satisfied).  The number of
shares  of Class A Common  Stock  issuable  upon  conversion  of a  Security  is
determined  as  follows:  divide the  principal  amount to be  converted  by the
Conversion  Price in effect on the Date of  Conversion;  round the result to the
nearest 1/100th of a share.

                                      -73-

<PAGE>

                  The initial Conversion Price is stated in the fourth paragraph
of the reverse of the  Securities  and is subject to  adjustment  as provided in
this Article.

                  A Holder may  convert a portion of a Security  equal to $1,000
principal amount or any integral multiple thereof.  Provisions of this Indenture
that apply to  conversion  of all of a Security  also apply to  conversion  of a
portion of it.

                  SECTION 12.2  Exercise of  Conversion  Privilege.  In order to
exercise the  conversion  privilege,  the Holder of any Security to be converted
shall  surrender  such Security to the Issuer at any time during usual  business
hours at its office or agency  maintained  for the  purpose as  provided in this
Indenture,  accompanied by a fully executed written notice, in substantially the
form set forth on the reverse of the Security, that the Holder elects to convert
such Security or a stated portion thereof constituting a multiple of the minimum
authorized  denomination  thereof,  and,  if such  Security is  surrendered  for
conversion  during the period  between  the close of business on any record date
for such  Security and the opening of business on the related  interest  payment
date (unless such Security shall have been called for redemption on a Redemption
Date or Change in Control Repurchase Date within such period or on such interest
payment  date),  accompanied  also by payment of an amount equal to the interest
payable on such interest  payment date on the portion of the principal amount of
the Security being  surrendered  for  conversion.  A Holder of any Security on a
record date for such Security who converts such Security on the related interest
payment  date will  receive  the  interest  payable on such  Security,  and such
converting  Holder  need  not  include  a  payment  for any such  interest  upon
surrender of such Security for conversion. Such notice shall also state the name
or names (with address) in which the certificate or  certificates  for shares of
Class A Common  Stock shall be issued.  Securities  surrendered  for  conversion
shall (if so required by the Issuer or the  Trustee) be duly  endorsed by, or be
accompanied  by  a  written  instrument  or  instruments  of  transfer  in  form
satisfactory  to the Issuer and the Trustee duly  executed by, the Holder or his
attorney duly authorized in writing. As promptly as

                                      -74-

<PAGE>

practicable  after the receipt of such notice and the surrender of such Security
as aforesaid, the Issuer shall, subject to the provisions of Section 12.7, issue
and deliver at such office or agency to such Holder,  or on his written order, a
certificate  or  certificates  for the  number of full  shares of Class A Common
Stock  issuable  on  such  conversion  of  Securities  in  accordance  with  the
provisions  of this Article and cash, as provided in Section 12.3, in respect of
any fraction of a share of Class A Common  Stock  otherwise  issuable  upon such
conversion.  Such conversion  shall be deemed to have been effected  immediately
prior  to the  close  of  business  on the  date  (herein  called  the  "Date of
Conversion")  on which such  notice  shall have been  received by the Issuer and
such  Security  shall  have been  surrendered  as  aforesaid,  and the Person or
Persons in whose name or names any  certificate  or  certificates  for shares of
Class A Common Stock shall be issuable upon such  conversion  shall be deemed to
have  become on the Date of  Conversion  the  holder or holders of record of the
shares represented thereby;  provided,  however,  that any such surrender on any
date  when  the  stock  transfer  books of the  Issuer  shall  be  closed  shall
constitute  the  person or persons  in whose  name or names the  certificate  or
certificates  for such  shares are to be issued as the  recordholder  or holders
thereof for all purposes at the opening of business on the next  succeeding  day
on  which  such  stock  transfer  books  are  open  but  such  conversion  shall
nevertheless  be at the  Conversion  Price in effect at the close of business on
the date when such Security shall have been so  surrendered  with the conversion
notice.  In the case of  conversion  of a  portion,  but  less  than  all,  of a
Security,  the Issuer shall  execute,  and the Trustee  shall  authenticate  and
deliver to the Holder  thereof,  at the  expense of the  Issuer,  a Security  or
Securities in the aggregate  principal amount of the unconverted  portion of the
Security surrendered.  Except as otherwise expressly provided in this Indenture,
no payment or adjustment  shall be made for interest accrued on any Security (or
portion  thereof)  converted or for  dividends or  distributions  on any Class A
Common Stock issued upon conversion of any Security;  provided, however, that in
the case of any Securities  which are converted after the close of business on a
relevant record date and on or prior to the next succeeding interest

                                      -75-

<PAGE>

payment  date,  installments  of interest  which are due and payable on the next
succeeding  interest payment date shall be payable on such interest payment date
notwithstanding such conversion (unless such Security shall have been called for
redemption on a Redemption  Date or Change in Control  Repurchase Date after the
close of  business  on such  record date and prior to the opening of business on
such interest payment date) and such interest (whether or not punctually paid or
duly provided for) shall be paid to the Holder of such Securities  registered as
such at the close of business on the  relevant  record date  according  to their
terms.  The  Issuer's  delivery of the fixed  number of shares of Class A Common
Stock into which the  Securities are  convertible  will be deemed to satisfy the
Issuer's  obligation  to pay the  principal  amount  of the  Securities  and all
accrued interest that has not previously been (or is not  simultaneously  being)
paid.  The Class A Common Stock is treated as issued first in payment of accrued
interest and then in payment of principal.

                  SECTION 12.3 Fractional Shares. Except as pro vided below, the
Issuer will not issue fractional  shares of Class A Common Stock upon conversion
of  Securities.  In  lieu  thereof,  in the  sole  discretion  of the  Board  of
Directors, either (a) such fractional interest will be rounded up to the nearest
full  share,  or (b) an  appropriate  amount will be paid in cash by the Issuer,
unless payment in cash is prohibited by the terms of the Issuer's  indebtedness,
in which case fractional shares may be issued. If the Issuer shall deliver cash,
such cash shall be in the amount of the fair market value (as  determined by the
Board of Directors) of such fractional interest. If more than one Security shall
be surrendered for conversion at one time by the same Holder, the number of full
shares  issuable upon  conversion  thereof shall be computed on the basis of the
aggregate  number  of  Securities,  or  the  specified  portions  thereof  to be
converted, so surrendered.

                  SECTION 12.4  Adjustment of Conversion  Price.  The Conversion
Price shall be subject to adjustment from time to time as follows:

                                      -76-

<PAGE>

                  (a) In case the  Issuer  shall  (1) pay a  dividend  or make a
         distribution on Class A Common Stock in shares of Class A Common Stock,
         (2)  subdivide  its  outstanding  shares of Class A Common Stock into a
         greater number of shares or (3) combine its outstanding shares of Class
         A Common Stock into a smaller number of shares, the Conversion Price in
         effect  immediately  prior to such action shall be adjusted as provided
         below so that the Holder of any  Security  thereafter  surrendered  for
         conversion shall be entitled to receive the number of shares of Class A
         Common Stock which he would have been  entitled to receive  immediately
         following  such action had such  Security  been  converted  immediately
         prior thereto. An adjustment made pursuant to this subsection (a) shall
         become  effective  immedi ately,  except as provided in subsection  (e)
         below,  after the record date in the case of a dividend or distribution
         and shall become effective  immediately after the effective date in the
         case of a subdivision or combination.

                  (b) In case the Issuer shall issue rights, warrants or options
         to all  holders  of Class A Common  Stock  entitling  them for a period
         expiring within 45 days after the record date therefor to subscribe for
         or  purchase  shares of Class A Common  Stock at a price per share less
         than the  current  market  price per share (as  determined  pursuant to
         subsection  (d) below) of the Class A Common  Stock on the record  date
         mentioned  below,  the  Conversion  Price shall be adjusted to a price,
         computed  to the nearest  cent,  so that the same shall equal the price
         determined by multiplying:

                           (1) the Conversion Price in effect  immediately prior
                  to the date of issuance of such rights,  warrants or option by
                  a fraction, of which

                           (2) the  numerator  shall be (A) the number of shares
                  of Class A Common Stock outstanding on the date of issuance of
                  such  rights,  warrants or options  immediately  prior to such
                  issuance, plus (B) the number of shares which the aggregate

                                      -77-

<PAGE>

                  offering  price of the total  number of shares so offered  for
                  subscription or purchase would purchase at such current market
                  price  (determined by multiplying  such total number of shares
                  by the exercise price of such rights,  warrants or options and
                  dividing  the  product  so  obtained  by such  current  market
                  price), and of which

                           (3) the denominator shall be (A) the number of shares
                  of Class A Common Stock outstanding on the date of issuance of
                  such rights,  warrants or options,  immediately  prior to such
                  issuance,  plus (B) the number of additional shares of Class A
                  Common  Stock  which  are  so  offered  for   subscription  or
                  purchase.

                  Such adjustment shall become effective immedi ately, except as
         provided  in  subsection  (e)  below,  after  the  record  date for the
         determination of Holders  entitled to receive such rights,  warrants or
         options.

                  (c) In case the  Issuer  shall  distribute  to all  holders of
         Class A Common  Stock  evidences  of  indebtedness,  equity  securities
         (including  equity interests in the Issuer's  Subsidiaries)  other than
         Class A Common Stock or other assets  (other than cash  dividends),  or
         shall  distribute  to all  holders  of  Class A  Common  Stock  rights,
         warrants  or options  to  subscribe  to  securities  (other  than those
         referred to in subsection (b) above and dividends and  distributions in
         connection  with the  liquidation,  dissolution  or  winding  up of the
         Issuer),  then in each such case the Conversion Price shall be adjusted
         so that the same shall equal the price  determined by  multiplying  the
         Conversion  Price  in  effect  immediately  prior  to the  date of such
         distribution  by a fraction of which the numerator shall be the current
         market price per share (determined as provided in subsection (d) below)
         of the Class A Common Stock on the record date mentioned below less the
         then fair market value (as determined by the Board of Directors,  whose
         determination  shall be conclusive  evidence of such fair market value,
         and

                                      -78-

<PAGE>

         described in a Board  Resolution filed with the Trustee) of the portion
         of the assets,  evidences  of  indebtedness  and equity  securities  so
         distributed  or  of  such  subscription  rights,  warrants  or  options
         applicable  to one  share  of Class A Common  Stock,  and of which  the
         denominator shall be such current market price per share of the Class A
         Common Stock.  For the purposes of this subsection (c), in the event of
         a  distribution  of shares of capital stock or other  securities of any
         Subsidiary  as a dividend on shares of Class A Common  Stock,  the then
         fair  market  value of the shares of other  securities  so  distributed
         shall be deemed to be the market value  (determined as provided  above)
         of such  shares  or other  securities.  Such  adjustment  shall  become
         effective  immediately,  except as  provided in  subsection  (e) below,
         after the record date for the determination of stockholders entitled to
         receive such distribution.

                  (d) For the purpose of any computation  under  subsections (b)
         and (c) above,  the  current  market  price per share of Class A Common
         Stock on any date  shall be deemed to be the  average  of the Last Sale
         Prices  of a share  of Class A Common  Stock  for the five  consecutive
         Trading  Days  commencing  not more than 20 Trading  Days  before,  and
         ending not later than, the earlier of the date in question and the date
         before  the "ex" date with  respect  to the  issuance  or  distribution
         requiring such  computation.  For purposes of this paragraph,  the term
         "'ex' date",  when used with  respect to any issuance or  distribution,
         means the first date on which the Class A Common Stock  trades  regular
         way on the principal national  securities exchange on which the Class A
         Common  Stock is listed or  admitted to trading (or if not so listed or
         admitted  on NASDAQ or a  similar  organization  if NASDAQ is no longer
         reporting  trading  information)  without  the  right to  receive  such
         issuance or distribution.

                  (e) In any case in which this  Section  shall  require that an
         adjustment be made immediately follow ing a record date, the Issuer may
         elect to defer the

                                      -79-

<PAGE>

         effectiveness  of such  adjustment  (but in no event until a date later
         than the effective  time of the event giving rise to such  adjustment),
         in which case the Issuer shall, with respect to any Security  converted
         after such  record date and before  such  adjustment  shall have become
         effective (i) defer making any cash payment pursuant to Section 12.3 or
         issuing to the Holder of such  Security the number of shares of Class A
         Common Stock and other capital  stock of the Issuer  issuable upon such
         conversion  in excess of the  number of shares of Class A Common  Stock
         and other capital stock of the Issuer  issuable  thereupon  only on the
         basis of the Conversion  Price prior to adjustment,  and (ii) not later
         than five  Business  Days  after  such  adjustment  shall  have  become
         effective,  pay to such Holder the appropriate cash payment pursuant to
         Section 12.3 and issue to such Holder the additional  shares of Class A
         Common  Stock and other  capital  stock of the Issuer  issuable on such
         conversion.

                  (f) No adjustment in the Conversion Price shall be required if
         Securityholders  are to participate  in the  transaction on a basis and
         with  notice  that the  Board of  Directors  determines  to be fair and
         appropri ate in light of the basis and notice on which holders of Class
         A  Common  Stock  participate  in  the  transaction.  In  addition,  no
         adjustment  in the  Conversion  Price  shall be  required  unless  such
         adjustment  would require an increase or decrease of at least 1% in the
         Conversion Price; provided that any adjustments which by reason of this
         subsection (f) are not required to be made shall be carried forward and
         taken into account in any subsequent adjustment. All calculations under
         this  Article  shall  be made  to the  nearest  cent or to the  nearest
         one-hundredth of a share, as the case may be.

                  (g)  Whenever  the  Conversion  Price is  adjusted  as  herein
         provided,  the Issuer shall promptly (i) file with the Trustee and each
         conversion agent an Officers'  Certificate setting forth the Conversion
         Price after such adjustment and setting forth in reasonable  detail the
         facts requiring such adjustment and the

                                      -80-

<PAGE>

         calculations on which the adjustment is based,  which certificate shall
         be conclusive  evidence of the correctness of such adjustment and which
         shall be made available by the Trustee to the Holders of Securities for
         inspection  thereof,  (ii)  mail or cause to be mailed a notice of such
         adjustment, setting forth the adjusted Conversion Price and the date on
         which such adjustment  became or becomes  effective,  to each Holder of
         Securities at his address as the same appears on the registry  books of
         the Issuer.

                  To the extent  permitted  by law, the Issuer from time to time
may  reduce  the  Conversion  Price by any  amount for any period of at least 20
days, if the Board of Directors  has made a  determination  that such  reduction
would be in the best  interests  of the  Issuer,  which  determination  shall be
conclusive.  In such case, the Issuer shall give at least 15 days' notice of the
reduction. In addition, at its option, the Issuer may make such reduction in the
Conversion  Price as the Board of Directors deems advisable to avoid or diminish
any income tax to holders of Class A Common Stock resulting from any dividend or
distribution  of stock (or rights to acquire stock) or from any event treated as
such for income tax purposes.

                  SECTION 12.5  Continuation of Conversion  Privilege in Case of
Reclassification,  Reorganization,  Change,  Merger,  Consolidation  or  Sale of
Assets.  If any transaction shall occur,  including  without  limitation (i) any
recapitalization  or  reclassification  of shares of Class A Common Stock (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 of the Class
A Common  Stock),  (ii) any  consolidation  or merger of the Issuer with or into
another  person or any merger of another  person  into the Issuer  (other than a
consolidation or merger that does not result in a reclassification,  conversion,
exchange or cancellation of Class A Common Stock), (iii) any sale or transfer of
all or  substantially  all of the assets of the Issuer,  or (iv) any  compulsory
share  exchange,  pursuant to any of which holders of Class A Common Stock shall
be entitled to receive other securities, cash or other

                                      -81-

<PAGE>

property,  then  appropriate  provision shall be made so that the Holder of each
Security  then  Outstanding  shall have the right  thereafter  to  convert  such
Security only into the kind and amount of the securities, cash or other property
that would have been  receivable upon such  recapitalization,  reclassification,
consolidation,  merger,  sale,  transfer  or share  exchange  by a holder of the
number  of shares  of Class A Common  Stock  issuable  upon  conversion  of such
Security   immediately   prior  to  such   recapitalization,   reclassification,
consolidation,  merger, sale, transfer or share exchange, after giving effect to
any adjustment in the conversion  price in accordance with this  Indenture.  The
company  formed by such  consolidation  or  resulting  from such  merger or that
acquires such assets or that acquires the Issuer's  shares,  as the case may be,
shall make provisions in its certificate of incorporation  or other  constituent
document to establish such right.  Such  certificate of  incorporation  or other
constituent  document shall provide for adjustments  that, for events subsequent
to the effective date of such certificate of incorporation or other  constituent
documents,  shall be as nearly  equivalent as may be practicable to the relevant
adjustments provided for in Section 12.4 and in this Section.

                  SECTION 12.6  Notice of Certain Events.  In case:

                  (a)  the  issuer  shall  declare  a  dividend  (or  any  other
         distribution)  payable to the  holders of Class A Common  Stock  (other
         than cash dividends and dividends payable in Class A Common Stock); or

                  (b) the Issuer shall  authorize the granting to the holders of
         Class A Common Stock of rights, warrants or options to subscribe for or
         purchase  any  shares  of stock of any  class or of any  other  rights,
         warrants or options; or

                  (c) the Issuer shall authorize any reclassifica tion or change
         of the Class A Common Stock (other than a subdivision or combination of
         its  outstanding  shares  of  Class A Common  Stock or a change  in par
         value, or from par value to no par value, or from no par value to

                                      -82-

<PAGE>

         par  value),  or any  consolidation  or merger to which the Issuer is a
         party and for which  approval  of any stock  holders  of the  Issuer is
         required,  or the sale or  conveyance of all or  substantially  all the
         property or business of the Issuer; or

                  (d) there  shall be  proposed  any  voluntary  or  involuntary
         dissolution, liquidation or winding-up of the Issuer;

then,  the Issuer shall cause to be filed with the  Trustee,  and, if other than
the Corporate  Trust Office of the Trustee,  at the office or agency  maintained
for the purpose of conversion of the  Securities as provided in Section 2.3, and
shall  cause to be mailed to each  Holder of  Securities,  at his  address as it
shall appear on the registry books of the Issuer, as promptly as possible but in
any event at least 20 days before the date hereinafter specified (or the earlier
of the dates  hereinafter  specified,  in the  event  that more than one date is
specified),  a notice  stating  the date on which (1) a record is expected to be
taken for the  purpose  of such  dividend,  distribution,  rights,  warrants  or
options,  or if a record is not to be taken, the date as of which the holders of
Class A Common  Stock of record to be entitled to such  dividend,  distribution,
rights or warrants are to be determined,  or (2) such reclassification,  change,
consolidation,  merger, sale, transfer, conveyance, dissolution,  liquidation or
winding-up is expected to become  effective and the date, if any is to be fixed,
as of which it is expected  that holders of Class A Common Stock of record shall
be entitled to exchange  their shares of Class A Common Stock for  securities or
other property deliverable upon such  reclassification,  change,  consolidation,
merger, sale, transfer, conveyance, dissolution, liquidation or winding-up.

                  SECTION 12.7 Taxes on Conversion. The issuance and delivery of
certificates  for shares of Class A Common  Stock on  conversion  of  Securities
shall be made without  charge to the  converting  Holder of Securities  for such
certificates  or for any  documentary,  stamp or similar issue or transfer taxes
payable to the United States of America or

                                      -83-

<PAGE>

any political subdivision or taxing authority thereof in respect of the issuance
or delivery of such certificates;  provided,  however, that the Issuer shall not
be  required  to pay any tax which may be payable  in  respect  of any  transfer
involved in the issuance of certificates for shares of Class A Common Stock, and
no such issue or delivery  shall be made unless and until the Person  requesting
such issue or delivery  has paid to the Issuer the amount of any such tax or has
established, to the satisfaction of the Issuer, that such tax has been paid.

                  SECTION  12.8  Issuer to  Provide  Class A Common  Stock.  The
Issuer  covenants that it will reserve and keep available,  free from preemptive
rights,  out of its  authorized but unissued  shares,  solely for the purpose of
issue upon  conversion of Securities as herein  provided,  sufficient  shares of
Class A Common Stock to provide for the conversion of the  Securities  from time
to time as such Securities are presented for conversion.

                  If any shares of Class A Common  Stock to be reserved  for the
purpose of conversion  of  Securities  hereunder  require  registration  with or
approval  of any  governmental  authority  under any Federal or State law before
such shares may be validly issued or delivered upon conversion,  then the Issuer
covenants that it will in good faith and as expeditiously  as possible  endeavor
to secure such registration or approval, as the case may be; provided,  however,
that  nothing  in  this  Section  shall  be  deemed  to  affect  in any  way the
obligations  of the Issuer to convert  Securities  into Class A Common  Stock as
provided in this Article.

                  Before  taking  any action  which  would  cause an  adjustment
reducing the Conversion  Price below the then par value,  if any, of the Class A
Common  Stock,  the Issuer  will take all  corporate  action  which may,  in the
Opinion of  Counsel,  be  necessary  in order that the  Issuer may  validly  and
legally  issue fully paid and  non-assessable  shares of Class A Common Stock at
such adjusted Conversion Price.

                                      -84-

<PAGE>

                  The Issuer  covenants  that all shares of Class A Common Stock
which  may be issued  upon  conversion  of  Securities  will upon  issue be duly
authorized,  validly issued and fully paid and  non-assessable by the Issuer and
free of  preemptive  rights  and of any lien or adverse  claim and that,  if the
Class A Common  Stock is then  listed on any  national  securities  exchange  or
quoted on NASDAQ,  the shares of Class A Common  Stock  which may be issued upon
conversion of Securities will be similarly  listed or quoted at the time of such
issuance.

                  The Issuer  covenants  that,  upon conversion of Securities as
herein provided, there will be credited to Class A Common Stock par capital from
the  consideration  for which the shares of Class A Common Stock  issuable  upon
such conversion are issued an amount per share of Class A Common Stock so issued
as determined by the Board of Directors, which amount shall not be less than the
amount  required by law and by the Issuer's  certificate  of  incorporation,  as
amended,  as in effect on the date of such conversion.  For the purposes of this
covenant the net  proceeds  received by the Issuer from the issuance and sale of
the Securities  converted,  less any cash conversion,  shall be deemed to be the
amount of  consideration  for which the shares of Class A Common Stock  issuable
upon such conversion are issued.

                  SECTION 12.9 Disclaimer of Responsibility for Certain Matters.
Neither the Trustee nor any  Conversion  Agent or agent of the Trustee  shall at
any time be under any duty or  responsibility  to any  Holder of  Securities  to
determine  whether  any facts exist  which may  require  any  adjustment  of the
Conversion  Price, or with respect to the Officers'  Certificate  referred to in
Section 12.4(g),  or with respect to the nature or extent of any such adjustment
when  made,  or  with  respect  to the  method  employed,  or  herein  or in any
supplemental  indenture provided to be employed, in making the same. Neither the
Trustee  nor any  Conversion  Agent  nor  any  agent  of the  Trustee  shall  be
accountable with respect to the validity,  registration,  listing,  or value (or
the kind or amount) of any shares of Class A Common Stock,  or of any securities
or cash or other property, which may at any time be issued or delivered upon the
conversion of any

                                      -85-

<PAGE>

Security;  and  neither  the  Trustee  nor  any  agent  of the  Trustee  nor any
Conversion  Agent makes any  representation  with respect  thereto.  Neither the
Trustee  nor any  Conversion  Agent  nor  any  agent  of the  Trustee  shall  be
responsible  for any failure of the Issuer to make any cash payment or to issue,
register  the transfer of or deliver any shares of Class A Common Stock or stock
certificates or other  securities or property upon the surrender of any Security
for the purpose of  conversion  or,  subject to Sections  5.1 and 5.2, to comply
with any of the covenants of the Issuer contained in this Article.

                  SECTION  12.10 Return of Funds  Deposited  for  Redemption  of
Converted  Securities.  Any funds which at any time shall have been deposited by
the Issuer or on its behalf with the Trustee or any other  Paying  Agent for the
purpose of paying the  principal  of and interest on any of the  Securities  and
which shall not be required for such purposes  because of the conversion of such
Securities,  as provided in this Article, shall after such conversion,  upon the
written  request of the  Issuer,  be repaid to the Issuer by the Trustee or such
other Paying Agent.

                                ARTICLE THIRTEEN

               RIGHT TO REQUIRE REDEMPTION UPON CHANGE IN CONTROL

                  SECTION 13.1 Right to Require Redemption. If at any time there
shall occur any Change in Control (as  defined  below) of the Issuer,  then each
Holder shall have the right, at such Holder's  option,  to require the Issuer to
redeem,  and upon the exercise of such right the Issuer shall redeem, all or any
part of such  Holder's  Securities  that is  $1,000 in  principal  amount or any
integral multiple thereof, on the date (the "Change in Control Repurchase Date")
that is 45 days after the date of the  Issuer  Notice  (as  defined  below) at a
price in cash equal to the  principal  amount  thereof,  and  accrued and unpaid
interest to the Repurchase Date (the "Change in Control Repurchase Price").

                                      -86-

<PAGE>

                  SECTION 13.2 Notices;  Method of Exercising  Redemption Right,
etc. (a) Unless the Issuer shall have theretofore  called for redemption all the
Securities then  Outstanding  pursuant to Article Eleven,  on or before the 30th
day after the  occurrence of a Change in Control,  the Issuer or, at the request
of the  Issuer,  the  Trustee,  shall  forward  to all  holders of record of the
Securities a notice (the  "Issuer  Notice") of the  occurrence  of the Change in
Control and of the redemption right set forth herein arising as a result thereof
in the manner  provided in Section 10.4 hereof.  The Issuer shall also deliver a
copy of the Issuer Notice to the Trustee prior to or promptly  after the mailing
of such Issuer Notice.

                  Each Issuer Notice shall state:

                  (1) the Change in Control Repurchase Date;

                  (2) the date by which the  Securities  with  respect  to which
         such  right is  being  exercised  and the  irrevocable  written  notice
         referred to in Section 13.2(b) must be delivered to the Trustee;

                  (3) the  Change in Control  Repurchase  Price,  including  and
         accrued interest, if any;

                  (4) a description of the procedure  which a Holder must follow
         to exercise a  redemption  right  including  a form of the  irrevocable
         written notice referred to in Section 13.2(b); and

                  (5) the Conversion Price then in effect, the date on which the
         right to convert the principal  amount of the Securities to be redeemed
         will  terminate  and the place or places where such  Securities  may be
         surrendered for conversion.

                  No  failure  of the  Issuer to give the  Issuer  Notice or any
defect therein shall limit any Holder's right to exercise a redemption  right or
affect the validity of the proceedings for the redemption of Securities.

                                      -87-

<PAGE>

                  (b) To exercise a redemption  right, a Holder shall deliver to
the  Trustee on or before  the 30th day after the date of the Issuer  Notice (i)
irrevocable  written notice of the Holder's exercise of such right, which notice
shall set forth  the name of the  Holder,  the  amount of the  Securities  to be
redeemed (which shall be in any authorized  denomination),  and a statement that
an election to exercise the redemption right is being made thereby, and (ii) the
Securities with respect to which the redemption right is being  exercised,  duly
endorsed for transfer to the Issuer.  Securities held by a securities depositary
may be  delivered  in such other  manner as may be agreed to by such  securities
depositary and the Issuer. Such written notice shall be irrevocable.  Subject to
the provisions of subsection (d) below,  Securities  surrendered  for redemption
together with such irrevocable written notice shall cease to be convertible from
the date of delivery of such notice.  If the Change in Control  Repurchase  Date
falls after the record date and before the following  interest payment date, any
Securities to be redeemed must be  accompanied  by payment of an amount equal to
the interest  thereon which the registered  Holder thereof is to receive on such
interest  payment date,  and,  notwithstanding  such  redemption,  such interest
payment  will be made by the  Issuer to the  registered  Holder  thereof  on the
applicable record date.

                  (c) In the event a  redemption  right  shall be  exercised  in
accordance  with the terms hereof,  the Issuer shall pay or cause to be paid the
Change in  Control  Repurchase  Price in cash,  to the  Holder on the  Change in
Control  Repurchase  Date.  The principal of and accrued  interest on Securities
payable  at the  Change in  Control  Repurchase  Price on the  Change in Control
Repurchase  Date  shall  be  considered  to be  principal  due on such  date for
purposes of this Indenture, including Article Four.

                  (d) If any Security surrendered for redemption shall not be so
redeemed  on the Change in  Control  Repurchase  Date,  such  Security  shall be
convertible  at any time  from the  Change  in  Control  Repurchase  Date  until
redeemed and, until redeemed,  continue to bear interest to the extent permitted
by applicable law from the Change in Control

                                      -88-

<PAGE>

Repurchase Date at the same rate borne by such Security. The Issuer shall pay to
the Holder of such  Security the  additional  amount  arising as a result of the
provisions  of this Section  13.2(d) at the same time that it pays the Change in
Control   Repurchase  Price,  and  if  applicable  such  Security  shall  remain
convertible  into Class A Common  Stock  until the Change in Control  Repurchase
Price plus any additional amounts owing on such Security shall have been paid or
duly provided for.

                  (e) Any Security which is to be redeemed only in part shall be
surrendered  at any office or agency of the Issuer  designated  for that purpose
pursuant to Section 2.3 (with,  if the Issuer or the  Trustee so  requires,  due
endorsement by, or a written  instrument of transfer in form satisfactory to the
Issuer and the Trustee duly executed by, the Holder thereof or his attorney duly
authorized  in writing),  and the Issuer shall  execute,  and the Trustee  shall
authenticate  and deliver to the Holder of such Security without service charge,
a new Security or  Securities,  of any authorized  denomination  as requested by
such  Holder,  in  aggregate  principal  amount equal to and in exchange for the
unredeemed portion of the Security so surrendered.

                  SECTION  13.3  Definition  of Change in Control.  A "Change in
Control" is deemed to have  occurred when (i) any person or group other than one
or more of the Principal  Stockholders  (as  hereinafter  defined) or any person
employed by the Issuer in a  management  capacity as of February 9, 2000 (or any
group of which  any of them is a member,  collectively,  a  "Permitted  Owner"),
acquires  beneficial  ownership of,  directly or  indirectly,  shares of capital
stock of the Issuer  sufficient to entitle such person to exercise more than 50%
of the total  voting power of all classes of capital  stock  entitled to vote in
elections  of  directors  (whether by means of an exchange  offer,  liquidation,
tender   offer,   consolidation,    merger,    combination,    reclassification,
recapitalization or otherwise),  or (ii) the Issuer sells, leases,  exchanges or
transfers  (in one  transaction  or a series  of  related  transactions)  all or
substantially all of its assets to any

                                      -89-

<PAGE>

person or group (in each  instance,  as the term  "person" or "group" is used in
Section  13(d)(3)  or  14(d)(2)  of the  Securities  Exchange  Act of  1934,  as
amended), other than one or more Permitted Owners, provided that any transaction
described  in (i) or (ii)  (whether  or not in any such case to or  involving  a
Permitted Owner) that results in the Class A Common Stock (or a successor common
equity security into which the Securities become convertible pursuant to Section
12.4) no longer  being  listed on a national  securities  exchange  or traded on
NASDAQ shall also be  considered a Change in Control.  "Principal  Stockholders"
means Steven B. Dodge, Thomas H. Stoner, Hicks, Muse, Tate & Furst Incorporated,
Cox Telecom  Towers,  Inc.  and Clear  Channel  Communications,  Inc.  and their
Affiliates.

                  SECTION  13.4  Limitation  on  Right  to  Require  Redemption.
Notwithstanding  anything herein to the contrary, no Holder shall have any right
to require redemption pursuant to this Article if either (i) the Last Sale Price
(or if on any such  Trading  Day the Class A Common  Stock is not  quoted by any
organization referred to in the definition of Last Sale Price, the fair value of
the Class A Common Stock on such day, as conclusively determined by the Board of
Directors) on any five Trading Days during the 10 Trading Day period immediately
preceding  the date of the Change in Control  shall  equal or exceed 105% of the
Conversion  Price in effect on such  Trading  Days or (ii) with  respect  to any
transaction  described  in  clause  (i) of  Section  13.3,  or  any  transaction
described  in  clause  (ii) of  Section  13.3  (so long as such  transaction  is
accompanied  by  or  immediately   followed  by  the  complete  liquidation  and
dissolution  of the Issuer),  all the  consideration  to be paid for the Class A
Common  Stock  or the  assets,  as the  case  may  be,  in  the  transaction  or
transactions constituting the Change in Control (A) has an aggregate fair market
value of at least 105% of the  Conversion  Price with  respect to such  Holder's
Securities in effect  immediately  prior to the closing of such  transaction and
(B) consists of cash,  securities  traded on a national  securities  exchange or
quoted on NASDAQ or a combination of cash and securities.

                                      -90-

<PAGE>

                                ARTICLE FOURTEEN

                REPURCHASE OF SECURITIES AT OPTION OF THE HOLDER

                  SECTION  14.1  General.  Securities  shall be purchased by the
Issuer as of February 20, 2007 (the "Repurchase  Date"), at the repurchase price
(the "Repurchase Price") set forth in the form of Security attached as Exhibit A
hereto, at the option of the Holder thereof, upon:

                  (1) delivery to the Paying  Agent,  by the Holder of a written
         notice  of  purchase  (the  "Repurchase  Notice")  at any time from the
         opening of business  on the date that is 20 Business  Days prior to the
         Repurchase  Date until the close of  business  on the  Repurchase  Date
         stating:

                           (A) the certificate  number of the Security which the
                  Holder will deliver to be purchased,

                           (B)  the  portion  of  the  principal  amount  of the
                  Security which the Holder will deliver to be purchased,  which
                  portion must be $1,000 or an integral multiple thereof,

                           (C) that such  Security  shall be purchased as of the
                  Repurchase Date pursuant to the terms and conditions specified
                  in the Securities and in this Indenture, and

                           (D) in the  event  the  Issuer  elects,  pursuant  to
                  Section  14.2,  to pay the  Repurchase  Price,  in whole or in
                  part,  in shares of Class A Common  Stock but such  portion of
                  the  Repurchase  Price  shall  ultimately  be  payable to such
                  Holder  entirely  in cash  because  any of the  conditions  to
                  payment of the Repurchase Price in Class A Common Stock is not
                  satisfied  prior to the close of  business  on the  Repurchase
                  Date, as set forth in Section 14.4, whether such Holder elects
                  (i) to withdraw  such  Repurchase  Notice as to some or all of
                  the Securities to which such Repurchase Notice

                                      -91-

<PAGE>

                  relates (stating the principal amount and certificate  numbers
                  of the Securities as to which such  withdrawal  shall relate),
                  or (ii) to receive  cash in  respect of the entire  Repurchase
                  Price for all Securities  (or portions  thereof) to which such
                  Repurchase Notice relates; and

                  (2) delivery of such Security to the Paying Agent prior to, on
         or after the Repurchase Date (together with all necessary endorsements)
         at the offices of the Paying Agent,  such delivery being a condition to
         receipt  by the  Holder of the  Repurchase  Price  therefor;  provided,
         however,  that the  Repurchase  Price shall be so paid pursuant to this
         Article only if the Security so delivered to the Trustee  shall conform
         in all respects to the  description  thereof in the related  Repurchase
         Notice.

                  If a Holder,  in such  Holder's  Repurchase  Notice and in any
written notice of withdrawal  delivered by such Holder  pursuant to the terms of
Section  14.9,  fails to  indicate  such  Holder's  choice  with  respect to the
election set forth in clause (D) of Section 14.1(1), such Holder shall be deemed
to have  elected to receive  cash in  respect  of the  Repurchase  Price for all
Securities  subject to such Repurchase  Notice in the circumstances set forth in
such clause (D).

                  The Issuer shall purchase from the Holder thereof, pursuant to
this Article, a portion of a Security if the principal amount of such portion is
$1,000 or an integral  multiple of $1,000.  Provisions  of this  Indenture  that
apply to the  purchase of all of a Security  also apply to the  purchase of such
portion of such Security.

                  Any  purchase  by  the  Issuer  contemplated  pursuant  to the
provisions  of  this  Article  shall  be  consummated  by  the  delivery  of the
consideration  to be received by the Holder promptly  following the later of the
Repurchase Date and the time of delivery of the Security.

                                      -92-

<PAGE>

                  Notwithstanding  anything  herein to the contrary,  any Holder
delivering to the Paying Agent a Repurchase Notice  contemplated by this Section
14.1 shall have the right to withdraw such  Repurchase  Notice at any time prior
to the close of business on the Repurchase  Date by delivery of a written notice
of withdrawal to the Paying Agent in accordance with Section 14.9.

                  The  Paying  Agent  shall  promptly  notify  the Issuer of the
receipt by it of any Repurchase Notice or written notice of withdrawal thereof.

                  SECTION  14.2  Issuer's  Right to Elect  Manner of  Payment of
Repurchase Price. The Securities to be purchased pursuant to Section 14.1 may be
paid for, at the election of the Issuer,  in cash or Class A Common Stock, or in
any combination of cash and Class A Common Stock,  subject to the conditions set
forth in  Sections  14.3 and 14.4.  The Issuer  shall  designate,  in the Issuer
Repurchase  Notice delivered  pursuant to Section 14.5,  whether the Issuer will
purchase the Securities  for cash or Class A Common Stock,  or, if a combination
thereof,  the  percentages of the  Repurchase  Price of Securities in respect of
which it will pay in cash or Class A Common Stock; provided that the Issuer will
pay cash for fractional interests in Class A Common Stock unless payment in cash
is  prohibited  by the  terms  of  the  Issuer's  indebtedness,  in  which  case
fractional  shares may be issued.  For purposes of determining  the existence of
potential fractional interests, all Securities subject to purchase by the Issuer
held by a Holder  shall be  considered  together  (no matter  how many  separate
certificates  are to be presented).  Each Holder whose  Securities are purchased
pursuant to this Article  shall  receive the same  percentage of cash or Class A
Common Stock in payment of the Repurchase Price for such Securities,  except (i)
as  provided  in  Section  14.4 with  regard to the  payment  of cash in lieu of
fractional  shares of Class A Common Stock and (ii) in the event that the Issuer
is unable to purchase the  Securities  of a Holder or Holders for Class A Common
Stock  because any  necessary  qualifications  or  registrations  of the Class A
Common Stock under  applicable  state  securities  laws cannot be obtained,  the
Issuer may purchase the Securities of such Holder or

                                      -93-

<PAGE>

Holders for cash.  The Issuer may not change its  election  with  respect to the
consideration  (or components or  percentages of components  thereof) to be paid
once the Issuer has given its Issuer Repurchase Notice to Securityholders except
pursuant to this  Section  14.2 or  pursuant  to Section  14.4 in the event of a
failure to satisfy,  prior to the close of business on the Repurchase  Date, any
condition to the payment of the Repurchase  Price, in whole or in part, in Class
A Common Stock.

                  At least  three  Business  Days  before the Issuer  Repurchase
Notice Date,  the Issuer shall deliver an Officers'  Certificate  to the Trustee
specifying:

                  (1) the manner of payment selected by the Issuer,

                  (2) the information required by Section 14.5,

                  (3) if the Issuer  elects to pay the  Repurchase  Price,  or a
         specified  percentage  thereof,  in  Class A  Common  Stock,  that  the
         conditions  to such  manner of payment  set forth in Section  14.4 have
         been or will be complied with, and

                  (4) whether the Issuer  desires the Trustee to give the Issuer
         Repurchase Notice required by Section 14.5.

                  SECTION 14.3 Repurchase with Cash. On the Repurchase  Date, at
the option of the Issuer, the Repurchase Price of Securities in respect of which
a  Repurchase  Notice  pursuant to Section  14.1 has been given,  or a specified
percentage  thereof,  may be paid by the Issuer with cash equal to the aggregate
Repurchase Price of such Securities. If the Issuer elects to purchase Securities
with cash, the Issuer  Repurchase  Notice, as provided in Section 14.5, shall be
sent to Holders (and the  Depositary  shall  distribute to beneficial  owners as
required  by  applicable  law)  not  less  than 20  Business  Days  prior to the
Repurchase Date (the "Issuer Repurchase Notice Date").

                  SECTION 14.4 Payment by Issuance of Class A Common  Stock.  On
the Repurchase Date, at the option of the

                                      -94-

<PAGE>

Issuer,  the  Repurchase  Price of  Securities  in respect of which a Repurchase
Notice  pursuant  to Section  14.1 has been  given,  or a  specified  percentage
thereof,  may be paid by the  Issuer  by the  issuance  of a number of shares of
Class A Common Stock equal to the  quotient  obtained by dividing (i) the amount
of cash to which the  Securityholders  would have been  entitled  had the Issuer
elected  to pay all or such  specified  percentage,  as the case may be,  of the
Repurchase  Price of such Securities in cash by (ii) the Market Price of a share
of Class A Common Stock, subject to the next succeeding paragraph.

                  The Issuer will not issue a fractional share of Class A Common
Stock in payment of the Repurchase  Price.  Instead the Issuer will pay cash for
the current market value of the fractional  share. The current market value of a
fraction of a share shall be determined by multiplying  the Market Price by such
fraction and rounding the product to the nearest  whole cent.  It is  understood
that if a Holder elects to have more than one Security purchased,  the number of
shares  of Class A Common  Stock  shall be  based  on the  aggregate  amount  of
Securities to be purchased.

                  If  the  Issuer  elects  to  purchase  the  Securities  by the
issuance of shares of Class A Common Stock,  the Issuer  Repurchase  Notice,  as
provided in Section 14.5, shall be sent to the Holders (and the Depositary shall
distribute  to beneficial  owners as required by applicable  law) not later than
the Issuer Repurchase Notice Date.

                  The  Issuer's  right to exercise  its election to purchase the
Securities  pursuant to this  Article  through the issuance of shares of Class A
Common Stock shall be conditioned upon:

                  (1) the Issuer's not having given its Issuer Repurchase Notice
         of an election to pay  entirely in cash and its giving a timely  Issuer
         Repurchase Notice of election to purchase all or a specified percentage
         of the Securities with Class A Common Stock as provided herein;

                                      -95-

<PAGE>

                  (2) the  registration of the shares of Class A Common Stock to
         be issued in respect of the payment of the  Repurchase  Price under the
         Securities Act or the Exchange Act, in each case, if required;

                  (3)  any  necessary   qualification   or  registration   under
         applicable  state  securities laws or the  availability of an exemption
         from such qualification and registration; and

                  (4) the receipt by the Trustee of an Officers' Certificate and
         an Opinion of Counsel  each  stating that (A) the terms of the issuance
         of the Class A Common Stock are in conformity  with this  Indenture and
         (B) the  shares of Class A Common  Stock to be issued by the  Issuer in
         payment of the Repurchase Price in respect of Securities have been duly
         authorized and, when issued and delivered pursuant to the terms of this
         Indenture  in  payment  of  the  Repurchase  Price  in  respect  of the
         Securities, will be validly issued, fully paid and non- assessable and,
         to the best of such counsel's  knowledge,  free from preemptive rights,
         and, in the case of such Officers' Certificate, stating that conditions
         (1), (2) and (3) above and the information  publication requirement set
         forth in the second sentence of the next succeeding paragraph have been
         satisfied  and, in the case of such  Opinion of Counsel,  stating  that
         conditions (2) and (3) above have been satisfied.

                  Such Officers'  Certificate shall also set forth the number of
         shares of Class A Common  Stock to be issued for each $1,000  principal
         amount  of  Securities  and the Last  Sale  Price of a share of Class A
         Common  Stock on each Trading Day during the period  commencing  on the
         first  Trading  Day of the  period  during  which the  Market  Price is
         calculated  and ending on the  Repurchase  Date. The Issuer may pay the
         Repurchase  Price (or any portion thereof) in Class A Common Stock only
         if the information necessary to calculate the Market Price is published
         in  a  daily  newspaper  of  national  circulation.  If  the  foregoing
         conditions are not satisfied with

                                      -96-

<PAGE>

         respect to a Holder or Holders  prior to the close of  business  on the
         Repurchase  Date and the Issuer has elected to purchase the  Securities
         pursuant  to this  Article  through  the  issuance of shares of Class A
         Common Stock,  the Issuer shall pay the entire  Repurchase Price of the
         Securities of such Holder or Holders in cash.

                  The "Market  Price"  means the average of the Last Sale Prices
         of the Class A Common Stock for the five  Trading Day period  ending on
         (if the third  Business Day prior to the  Repurchase  Date is a Trading
         Day,  or if not,  then on the last  Trading  Day  prior  to) the  third
         Business Day prior to the Repurchase  Date,  appropriately  adjusted to
         take into account the occurrence,  during the period  commencing on the
         first of such  Trading  Days  during  such five  Trading Day period and
         ending on the  Repurchase  Date,  of any event  described  in  Sections
         12.4(a),  12.4(b) or 12.4(c),  subject,  however, to the conditions set
         forth in Section 12.4(f).

                  SECTION  14.5  Notice  of  Election.  The  Issuer's  notice of
election  to  purchase  with  cash or  Class A Common  Stock or any  combination
thereof  shall be sent to the Holders (and to  beneficial  owners as required by
applicable  law) in the manner provided in Section 10.4 at the time specified in
Section 14.3 or 14.4,  as  applicable  (the "Issuer  Repurchase  Notice").  Such
Issuer  Repurchase  Notice  shall state the manner of payment  elected and shall
contain the following information:

                  In the event the  Issuer  has  elected  to pay the  Repurchase
         Price (or a specified  percentage  thereof)  with Class A Common Stock,
         the Issuer Repurchase Notice shall:

                           (1)  state  that each  Holder  will  receive  Class A
                  Common Stock with a Market Price  determined as of a specified
                  date  prior to the  Repurchase  Date  equal to such  specified
                  percentage of the Repurchase  Price of the Securities  held by
                  such

                                      -97-

<PAGE>

                  Holder  (except  any  cash  amount  to  be  paid  in  lieu  of
                  fractional shares);

                           (2) set forth the  method of  calculating  the Market
                  Price of the Class A Common Stock as required by Section 14.4;
                  and

                           (3) state that,  because the Market  Price of Class A
                  Common Stock will be determined  prior to the Repurchase Date,
                  Holders will bear the market risk with respect to the value of
                  the  Class A Common  Stock to be  received  from the date such
                  Market Price is determined to the Repurchase Date.

                  In any case,  each Issuer  Repurchase  Notice shall  include a
         form of Repurchase Notice to be completed by a Securityholder and shall
         state:

                           (A) the Repurchase Price and the Conversion Price;

                           (B) the name and address of the Paying  Agent and the
                  Conversion Agent;

                           (C) that  Securities as to which a Repurchase  Notice
                  has been given may be  converted  pursuant  to Article  Twelve
                  only if the applicable Repurchase Notice has been withdrawn in
                  accordance with the terms of this Indenture;

                           (D) that Securities must be surrendered to the Paying
                  Agent to collect payment;

                           (E) that the Repurchase  Price for any security as to
                  which a  Repurchase  Notice has been  given and not  withdrawn
                  will be paid promptly  following  the later of the  Repurchase
                  Date and the time of surrender  of such  Security as described
                  in (D) above;

                                      -98-

<PAGE>

                           (F) the procedures the Holder must follow to exercise
                  rights  under this  Article and a brief  description  of those
                  rights;

                           (G) briefly, the conversion rights of the Securities;
                  and

                           (H)  the  procedures  for  withdrawing  a  Repurchase
                  Notice  (including,  without  limitation,  for  a  conditional
                  withdrawal  pursuant  to the terms of  Section  14.1(1)(D)  or
                  Section 14.9).

                  At the Issuer's  request,  the Trustee  shall give such Issuer
Repurchase  Notice in the Issuer's name and at the Issuer's  expense;  provided,
however,  that, in all cases, the text of such Issuer Repurchase Notice shall be
prepared by the Issuer.

                  Upon  determination  of the actual number of shares of Class A
Common Stock to be issued for each $1,000  principal  amount of Securities,  the
Issuer will publish such determination in a newspaper of national circulation.

                  SECTION 14.6  Covenants  of the Issuer.  All shares of Class A
Common Stock  delivered  upon purchase of the  Securities  shall be newly issued
shares or treasury shares, shall be duly authorized,  validly issued, fully paid
and  non-assessable  by the Issuer and shall be free of preemptive rights of any
lien or adverse claim.

                  If the Class A Common  Stock is then  listed  on any  national
securities  exchange or quoted on NASDAQ,  the shares of Class A Common Stock to
be issued to purchase  Securities will be similarly listed or quoted at the time
of such issuance.

                  SECTION  14.7  Procedure  upon  Repurchase.  The Issuer  shall
deposit cash (in respect of a cash purchase under Section 14.3 or for fractional
interests,  as applicable)  or shares of Class A Common Stock,  or a combination
thereof,  as  applicable,  at the time and in the manner as  provided in Section
14.10, sufficient to pay the

                                      -99-

<PAGE>

aggregate  Repurchase  Price of all Securities to be purchased on the Repurchase
Date pursuant to this Article. As soon as practicable after the Repurchase Date,
the Issuer shall deliver to each Holder entitled to receive Class A Common Stock
through the Paying Agent a certificate  for the number of full shares of Class A
Common Stock issuable in payment of the Repurchase Price and cash in lieu of any
fractional  interests.  The  Person in whose  name the  certificate  for Class A
Common Stock is  registered  shall be treated as a holder of record of shares of
Class A Common Stock on the Business Day following the Repurchase Date.  Subject
to Section  14.4,  no payment or  adjustment  will be made for  dividends on the
Class A Common  Stock  the  record  date for which  occurred  on or prior to the
Repurchase Date.

                  SECTION 14.8 Taxes. If a Holder of a Security is paid in Class
A Common Stock, the Issuer shall pay any documentary,  stamp or similar issue or
transfer  taxes  payable  to the  United  Sates  of  America  or  any  political
subdivision or taxing  authority  thereof in respect of the issuance or delivery
of such Class A Common Stock;  provided,  however,  that the Issuer shall not be
required to pay any tax which may be payable in respect of any transfer involved
in the issuance of shares of Class A Common Stock, and no such issue or delivery
shall be made unless and until the Person  requesting such issue or delivery has
paid to the  Issuer  or the  Paying  Agent  the  amount  of any  such tax or has
established,  to the  satisfaction of the Issuer or the Paying Agent,  that such
tax has been paid.  Nothing  herein shall  preclude  any income tax  withholding
required by law or regulations.

                  SECTION 14.9 Effect of Repurchase Notice.  Upon receipt by the
Paying Agent of the Repurchase  Notice, the Holder of the Security in respect of
which such Repurchase  Notice was given shall (unless such Repurchase  Notice is
withdrawn as specified in the following two  paragraphs)  thereafter be entitled
to  receive  solely the  Repurchase  Price with  respect to such  Security.  The
Repurchase  Price  shall be paid to such  Holder,  subject  to  receipt of funds
and/or securities by the Paying Agent,  promptly  following the later of (x) the
Repurchase Date with respect to such

                                      -100-

<PAGE>

Security  (provided the conditions in Section 14.1 have been  satisfied) and (y)
the time of delivery of such Security to the Paying Agent by the Holder  thereof
in the  manner  required  by  Section  14.1.  Securities  in  respect of which a
Repurchase  Notice  has been given by the Holder  thereof  may not be  converted
pursuant  to  Article  Twelve  on or  after  the  date of the  delivery  of such
Repurchase Notice unless such Repurchase Notice has first been validly withdrawn
as  specified in the  following  two  paragraphs.  The  principal of  Securities
payable as the Repurchase Price on the Repurchase Date shall be considered to be
principal  due on such date for purposes of this  Indenture,  including  Article
Four.

                  A  Repurchase  Notice may be  withdrawn  by means of a written
notice of  withdrawal  delivered to the office of the Paying Agent in accordance
with the  Repurchase  Notice at any time prior to the close of  business  on the
Repurchase Date specifying:

                  (1) the certificate number of the Security in respect of which
         such notice of withdrawal is being submitted;

                  (2) the principal amount of the Security with respect to which
         such notice of withdrawal is being submitted; and

                  (3) the  principal  amount,  if any,  of such  Security  which
         remains subject to the original Repurchase Notice and which has been or
         will be delivered for purchase by the Issuer.

                  A written  notice of withdrawal of a Repurchase  Notice may be
in the form set forth in the preceding  paragraph or may be in the form of (i) a
conditional withdrawal contained in a Repurchase Notice pursuant to the terms of
Section 14.1(1)(D) or (ii) a conditional  withdrawal  containing the information
set forth in Section  14.1(1)(D) and the preceding  paragraph and contained in a
written  notice of withdrawal  delivered to the Paying Agent as set forth in the
preceding paragraph.

                                      -101-

<PAGE>

                  There shall be no purchase of any Securities  pursuant to this
Article  (other than  through the issuance of Class A Common Stock in payment of
the Repurchase Price,  including cash in lieu of fractional shares) if there has
occurred (prior to, on or after, as the case may be, the giving,  by the Holders
of such  Securities,  of the required  Repurchase  Notice) and is  continuing an
Event of Default  (other than a default in the payment of the  Repurchase  Price
with respect to such  Securities).  The Paying Agent will promptly return to the
respective Holders thereof any Securities (x) with respect to which a Repurchase
Notice has been withdrawn in compliance with this  Indenture,  or (y) held by it
during  the  continuance  of an Event of  Default  (other  than a default in the
payment of the Repurchase  Price with respect to such Securities) in which case,
upon such return,  the Repurchase Notice with respect thereto shall be deemed to
have been withdrawn.

                  SECTION 14.10 Deposit of Repurchase Price. Prior to 11:00 a.m.
(New York City time) on the  Repurchase  Date the Issuer shall  deposit with the
Trustee or with one or more  Paying  Agents  (or, if the Issuer is acting as its
own Paying Agent,  shall segregate and hold in trust as provided in Section 2.3)
an amount of money (in immediately available funds if deposited on such Business
Day) or Class A Common  Stock,  if permitted  hereunder,  sufficient  to pay the
aggregate Repurchase Price of all of the Securities or portions thereof that are
to be purchased as of the Repurchase Date.

                  SECTION 14.11  Securities  Repurchased  in Part.  Any Security
which is to be purchased  only in part shall be surrendered at the office of the
Paying Agent (with,  if the Issuer or the Trustee so requires,  due  endorsement
by, or a written  instrument of transfer in form  satisfactory  to the Issuer or
the Trustee duly executed by, the Holder thereof or such Holder's  attorney duly
authorized  in writing)  and the Issuer  shall  execute  and the  Trustee  shall
authenticate and deliver to the Holder of such Security, without service charge,
a new Security or  Securities,  of any authorized  denomination  as requested by
such Holder in aggregate  principal  amount  equal to, and in exchange  for, the
portion

                                      -102-

<PAGE>

of the principal amount of the Security so surrendered which is not purchased.

                  SECTION  14.12  Issuer to  Comply  with  Securities  Laws upon
Purchase of Securities.  In connection with any offer to purchase or purchase of
Securities under this Article (provided that such offer or purchase  constitutes
an "issuer tender offer" for purposes of Rule 13e-4 (which term, as used herein,
includes any successor  provision thereto) under the Exchange Act at the time of
such offer or  purchase),  the Issuer  shall (i) comply with Rule 13e-4 and Rule
14e-1  under the  Exchange  Act,  (ii) file the related  Schedule  13E-4 (or any
successor schedule,  form or report) under the Exchange Act, and (iii) otherwise
comply with all Federal and state securities laws so as to permit the rights and
obligations  under this  Article to be  exercised  in the time and in the manner
specified in this Article.

                  SECTION  14.13  Repayment  to the Issuer.  The Trustee and any
Paying  Agent  shall  return to the  Issuer any cash or shares of Class A Common
Stock that remain  unclaimed as provided in Section 9.4,  together with interest
or  dividends,  if any,  thereon held by them for the payment of the  Repurchase
Price  upon  Issuer  Order;  provided,  however,  that to the  extent  that  the
aggregate  amount  of cash or shares of Class A Common  Stock  deposited  by the
Issuer pursuant to Section 14.10 exceeds the aggregate  Repurchase  Price of the
Securities  or portions  thereof which the Issuer is obligated to purchase as of
the  Repurchase  Date,  then  promptly  after the  Business  Day  following  the
Repurchase  Date the Trustee shall return any such excess to the Issuer together
with interest or dividends, if any, thereon.

                                      -103-

<PAGE>

                  IN WITNESS  WHEREOF,  the  parties  hereto  have  caused  this
Indenture to be duly executed, all as of February 15, 2000.

                                          AMERICAN TOWER CORPORATION

                                          By /s/ James S. Eisenstein
                                          Name:  James S. Eisenstein
                                          Title: Chief Development
                                                 Officer

Attest:

By /s/ Justin D. Benincasa
Name:  Justin D. Benincasa
Title: Vice President/
       Corporate Controller

                                          THE BANK OF NEW YORK, not in
                                               its individual capacity
                                               but solely as Trustee

                                          By /s/ Michael Culhane
                                          Name:  Michael Culhane
                                          Title: Vice President

<PAGE>

                                                                       EXHIBIT A

                           [FORM OF FACE OF SECURITY]

THE FOLLOWING LEGEND SHALL APPEAR ON THE FACE OF EACH
RESTRICTED SECURITY OTHER THAN ANY RESTRICTED GLOBAL
SECURITY:

                  THIS  SECURITY  (OR ITS  PREDECESSOR)  AND ANY  CLASS A COMMON
STOCK  ISSUED ON  CONVERSION  HEREOF HAVE NOT BEEN  REGISTERED  UNDER THE UNITED
STATES  SECURITIES ACT OF 1933, AS AMENDED (THE "SECURITIES  ACT"), OR ANY STATE
SECURITIES LAW AND MAY NOT BE OFFERED,  SOLD,  PLEDGED OR OTHERWISE  TRANSFERRED
EXCEPT  (A)(1) TO A PERSON WHO THE SELLER  REASONABLY  BELIEVES  IS A  QUALIFIED
INSTITUTIONAL  BUYER  WITHIN THE MEANING OF RULE 144A UNDER THE  SECURITIES  ACT
PURCHASING  FOR ITS OWN ACCOUNT OR FOR THE ACCOUNT OF A QUALIFIED  INSTITUTIONAL
BUYER IN A TRANSACTION MEETING THE REQUIREMENTS OF RULE 144A, (2) PURSUANT TO AN
EXEMPTION  FROM  REGISTRATION  UNDER THE  SECURITIES  ACT  PROVIDED  BY RULE 144
THEREUNDER  (IF  AVAILABLE),  OR  (3)  PURSUANT  TO  AN  EFFECTIVE  REGISTRATION
STATEMENT  UNDER THE SECURITIES  ACT, AND (B) IN ACCORDANCE  WITH ALL APPLICABLE
SECURITIES LAWS OF THE STATES OF THE UNITED STATES.

                  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 FOLLOWING LEGEND SHALL APPEAR ON THE FACE OF EACH
RESTRICTED GLOBAL SECURITY:

                  THE  SECURITIES  EVIDENCED  BY THIS GLOBAL  SECURITY (OR THEIR
PREDECESSORS)  AND ANY  CLASS A  COMMON  STOCK  ISSUED  ON  CONVERSION  OF THOSE
SECURITIES  HAVE NOT BEEN REGISTERED  UNDER THE UNITED STATES  SECURITIES ACT OF
1933, AS AMENDED (THE "SECURITIES ACT"), OR ANY STATE SECURITIES LAW AND MAY NOT
BE  OFFERED,   SOLD,  PLEDGED  OR  OTHERWISE   TRANSFERRED  IN  THE  ABSENCE  OF
REGISTRATION OR AN APPLICABLE EXEMPTION THEREFROM.

<PAGE>

                  EACH BENEFICIAL  OWNER OF AN INTEREST IN ANY OF THE SECURITIES
EVIDENCED BY THIS GLOBAL  SECURITY  (INCLUDING ANY PARTICIPANT IN THE DEPOSITARY
HOLDING  THE GLOBAL  SECURITY  THAT IS SHOWN AS HOLDING  SUCH AN INTEREST ON THE
RECORDS OF SUCH DEPOSITARY AND EACH BENEFICIAL OWNER THAT HOLDS THROUGH ANY SUCH
PARTICIPANT) AGREES FOR THE BENEFIT OF AMERICAN TOWER CORPORATION (THE "ISSUER")
THAT (I) ANY  BENEFICIAL  INTEREST IN THE  SECURITIES  AND ANY SHARES OF CLASS A
COMMON STOCK ISSUABLE UPON THEIR CONVERSION MAY BE RESOLD,  PLEDGED OR OTHERWISE
TRANSFERRED  ONLY  (A)(1) TO A PERSON WHO THE SELLER  REASONABLY  BELIEVES  IS A
QUALIFIED  INSTITUTIONAL  BUYER  WITHIN  THE  MEANING  OF RULE  144A  UNDER  THE
SECURITIES  ACT PURCHASING FOR ITS OWN ACCOUNT OR FOR THE ACCOUNT OF A QUALIFIED
INSTITUTIONAL  BUYER IN A TRANSACTION MEETING THE REQUIREMENTS OF RULE 144A, (2)
PURSUANT TO AN EXEMPTION FROM REGISTRATION  UNDER THE SECURITIES ACT PROVIDED BY
RULE 144 THEREUNDER (IF AVAILABLE), OR (3) PURSUANT TO AN EFFECTIVE REGISTRATION
STATEMENT  UNDER THE SECURITIES  ACT, AND (B) IN ACCORDANCE  WITH ALL APPLICABLE
SECURITIES LAWS OF THE STATES OF THE UNITED STATES AND (II) THE BENEFICIAL OWNER
WILL,  AND  EACH  SUBSEQUENT  BENEFICIAL  OWNER  OF AN  INTEREST  IN  ANY OF THE
SECURITIES  EVIDENCED  BY THIS  GLOBAL  SECURITY  OR ANY  CLASS A  COMMON  STOCK
ISSUABLE  UPON  CONVERSION  THEREOF IS REQUIRED TO,  NOTIFY ANY PURCHASER OF ANY
BENEFICIAL INTEREST IN THE SECURITIES OR SUCH CLASS A COMMON STOCK ISSUABLE UPON
ITS CONVERSION FROM IT OF THE RESALE RESTRICTIONS REFERRED TO IN (I) ABOVE.

                  EACH PURCHASER OF ANY BENEFICIAL INTEREST IN THE SECURITIES IS
HEREBY  NOTIFIED THAT THE SELLER OF SUCH  BENEFICIAL  INTEREST MAY BE RELYING ON
THE EXEMPTION FROM THE PROVISIONS OF SECTION 5 OF THE SECURITIES ACT PROVIDED BY
RULE 144A THEREUNDER.

THE FOLLOWING LEGEND SHALL APPEAR ON THE FACE OF EACH GLOBAL
SECURITY:

                  THIS SECURITY IS A GLOBAL  SECURITY  WITHIN THE MEANING OF THE
INDENTURE  HEREINAFTER  REFERRED  TO  AND  IS  REGISTERED  IN  THE  NAME  OF THE
DEPOSITARY OR A NOMINEE OF THE  DEPOSITARY,  WHICH MAY BE TREATED BY THE ISSUER,
THE TRUSTEE

                                       -2-

<PAGE>

AND ANY AGENT THEREOF AS OWNER AND HOLDER OF THIS SECURITY FOR ALL PURPOSES.

THE FOLLOWING  LEGEND SHALL APPEAR ON THE FACE OF EACH GLOBAL
SECURITY FOR WHICH THE DEPOSITORY TRUST COMPANY IS TO BE THE
DEPOSITARY:

                  UNLESS  THIS   CERTIFICATE   IS  PRESENTED  BY  AN  AUTHORIZED
REPRESENTATIVE OF THE DEPOSITORY TRUST COMPANY, A NEW YORK CORPORATION  ("DTC"),
TO THE ISSUER OR ITS AGENT FOR REGISTRATION OF TRANSFER,  EXCHANGE,  OR PAYMENT,
AND ANY  CERTIFICATE  ISSUED IS  REGISTERED IN THE NAME OF CEDE & CO. OR IN SUCH
OTHER  NAME AS IS  REQUESTED  BY AN  AUTHORIZED  REPRESENTATIVE  OF DTC (AND ANY
PAYMENT  IS MADE TO CEDE & CO. OR TO SUCH  OTHER  ENTITY AS IS  REQUESTED  BY AN
AUTHORIZED REPRESENTATIVE OF DTC), ANY TRANSFER, PLEDGE, OR OTHER USE HEREOF FOR
VALUE OR  OTHERWISE BY OR TO ANY PERSON IS WRONGFUL  INASMUCH AS THE  REGISTERED
OWNER HEREOF, CEDE & CO., HAS AN INTEREST HEREIN.

                                       -3-

<PAGE>

No.                                                                 $___________
                                                                     [CUSIP NO.]

                           American Tower Corporation

                         5.0% Convertible Notes Due 2010

                  American Tower Corporation (the "Issuer"),  for value received
hereby  promises to pay to _________ or registered  assigns the principal sum of
____________________  Dollars (which  principal  amount may from time to time be
increased or decreased to such other principal  amounts  (which,  taken together
with the principal amounts of all other Outstanding Securities, shall not exceed
$450,000,000 in the aggregate at any time) by adjustments made on the records of
the Trustee  hereinafter  referred to in accordance  with the  Indenture) at the
Issuer's office or agency for said purpose in the Borough of Manhattan, The City
of New York, on February 15, 2010, in such coin or currency of the United States
of America as at the time of payment  shall be legal  tender for the  payment of
public and private debts, and to pay interest,  semi-annually on February 15 and
August 15 of each year and at maturity,  on said  principal  sum in like coin or
currency at the rate per annum set forth above  beginning on August 15, 2000, or
from the most recent date to which  interest has been paid or duly  provided for
on the Securities. The interest so payable on any February 15 or August 15 will,
except as otherwise provided in the Indenture referred to on the reverse hereof,
be paid to the person in whose name this  Security is registered at the close of
business on the January 31 or July 31 preceding  such  February 15 or August 15,
whether or not such day is a business  day;  provided that interest may be paid,
at the  option  of the  Issuer,  by  mailing  a check  therefor  payable  to the
registered  Holder  entitled  thereto  at his last  address as it appears on the
Security register.

                  Reference is made to the further  provisions  set forth on the
reverse hereof, including without limitation

                                       -4-

<PAGE>

provisions  giving the Holder  hereof the right to convert  this  Security  into
Class A Common  Stock of the Issuer on the terms and  subject to the  conditions
and limitations  referred to on the reverse  hereof,  as more fully specified in
the  Indenture.  Such further  provisions  shall for all purposes  have the same
effect as though fully set forth at this place.

                  This  Security  shall  not be valid or  obligatory  until  the
certificate of authentication  hereon shall have been duly signed by the Trustee
acting under the Indenture.

                  IN WITNESS  WHEREOF,  the Issuer has caused this instrument to
be duly executed under its corporate seal.

Dated:  February 15, 2000

[Seal]

                                             AMERICAN TOWER CORPORATION

                                             By____________________________

                                             By____________________________

                                       -5-

<PAGE>

                          [FORM OF REVERSE OF SECURITY]

                           American Tower Corporation

                         5.0% Convertible Notes Due 2010

                  This  Security  is one  of a duly  authorized  issue  of  debt
securities  of the Issuer,  limited to up to the aggregate  principal  amount of
$400,000,000,  or up to $450,000,000 if an option is fully exercised  (except as
otherwise  provided  in the  Indenture  defined  below),  issued or to be issued
pursuant to an indenture dated as of February 15, 2000 (the  "Indenture"),  duly
executed and  delivered  by the Issuer to The Bank of New York,  as Trustee (the
"Trustee").  Reference  is  hereby  made to the  Indenture  and  all  indentures
supplemental  thereto for a description  of the rights,  limitations  of rights,
obligations, duties and immunities thereunder of the Trustee, the Issuer and the
Holders  (the word  "Holders"  or  "Holder"  meaning the  registered  Holders or
registered  Holder)  of the  Securities.  Terms used but not  otherwise  defined
herein shall have the meanings assigned thereto in the Indenture.

                  In case an Event of  Default,  as  defined  in the  Indenture,
shall have occurred and be  continuing,  the principal of all the Securities and
interest accrued thereon may be declared due and payable, in the manner and with
the  effect,  and subject to the  conditions,  provided  in the  Indenture.  The
Indenture  provides that in certain events a declaration of default,  a default,
or the consequences of either of them may be waived by the Holders of a majority
in  aggregate  principal  amount of the  Securities  then  outstanding  except a
default in the  payment of  principal,  Change in  Control  Repurchase  Price or
Repurchase Price of or premium,  if any, or interest on any of the Securities or
in respect  of the  conversion  of any of the  Securities.  Any such  consent or
waiver  by the  Holder of this  Security  (unless  revoked  as  provided  in the
Indenture)  shall be conclusive and binding upon such Holder and upon all future
Holders  and owners of this  Security  and any  Security  which

                                       -6-

<PAGE>

may be issued in exchange or  substitution  hereof,  whether or not any notation
thereof is made upon this Security or such other Securities.

                  The Indenture permits the Issuer and the Trustee,  without the
consent of any of the Holders under the  circumstances  described in Section 7.1
of the  Indenture,  and with  the  consent  of the  Holders  of not less  than a
majority  in  aggregate   principal   amount  of  the  Securities  at  the  time
outstanding,  evidenced as in the Indenture  provided,  to execute  supplemental
indentures adding any provisions to or changing in any manner or eliminating any
of the provisions of the Indenture or of any supplemental indenture or modifying
in any manner the rights of the Holders of the Securities; provided that no such
supplemental  indenture shall (a) extend the final maturity of any Security,  or
reduce the principal amount thereof or premium,  if any, thereon,  or reduce the
rate or extend the time of payment of interest  thereon,  or any premium payable
on the redemption  thereof, or change the place of payment where, or the coin or
currency in which, any principal,  premium or interest is payable,  or reduce or
alter the method of computation of any amount payable on redemption,  repurchase
or  repayment  thereof  (or the time at which  such  redemption,  repurchase  or
repayment  may be  made),  or  impair  or  adversely  affect  the  right  of any
Securityholder  to  institute  suit for the  payment  or  conversion  thereof or
adversely  affect the right to convert the Securities  into Class A Common Stock
of the Issuer,  in each case,  without the consent of the Holder of the Security
so affected; provided no consent of any Holder of any Security will be necessary
to permit the Trustee and the Issuer to execute  supplemental  indentures  under
the circumstances  provided in Section 7.1(e) and Section 12.5 of the Indenture,
or (b) reduce the aforesaid  percentage in principal  amount of Securities,  the
consent of the Holders of which is required for any such supplemental indenture,
without the consent of the Holders of each  Security so affected,  or (c) reduce
the  percentage  of  Securities  necessary  to consent to waive any past default
under the Indenture to less than a majority,  without the consent of the Holders
of each  Security  so  affected;  or (d)  modify  any of the  provisions  of the
Indenture  relating  to  supplemental

                                      -7-
<PAGE>

indentures  or waivers  of past  defaults,  except to  increase  any  percentage
provided for in Section 4.10 or Section 7.2 of the  Indenture or to provide that
certain other  provisions of the Indenture  cannot be modified or waived without
the consent of the Holder of each Security affected thereby.

                  Subject to the provisions of the Indenture, the Holder of this
Security has the right, at his option, at any time until and including,  but not
after the close of business on,  February 15, 2010  (except  that,  in case this
Security or a portion hereof shall be called for redemption and the Issuer shall
not thereafter default in making due provision for the payment of the redemption
price,  such right shall terminate with respect to this Security or such portion
hereof at the close of business on the  Business Day prior to the date fixed for
redemption),  to convert the principal  amount of this Security,  or any portion
thereof which is $1,000 or an integral  multiple of $1,000,  into fully paid and
non-assessable  shares of Class A Common  Stock of the  Issuer,  as said  shares
shall be  constituted  at the date of  conversion,  at the  conversion  price of
$51.50 in principal  amount of Securities  for each share of such Class A Common
Stock, or at the adjusted  conversion  price in effect at the date of conversion
if an adjustment has been made,  determined as provided in the  Indenture,  upon
surrender  of this  Security to the Issuer at the office or agency of the Issuer
maintained  for that purpose in the Borough of Manhattan,  The City of New York,
together with a fully executed notice substantially in the form set forth at the
foot hereof that the Holder  elects so to convert this  Security (or any portion
hereof which is an integral  multiple of $1,000  principal  amount) and, if this
Security is surrendered  for  conversion  during the period between the close of
business on January 31 or July 31 in any year and the opening of business on the
following  February 15 or August 15 and has not been called for  redemption on a
redemption  date within  such  period (or on such  February 15 or August 15), or
within five days after such period, accompanied by payment of an amount equal to
the interest payable on such February 15 or August 15 on the principal amount of
the  Security  being  surrendered  for  conversion.  Except as  provided  in the
preceding  sentence or as  otherwise

                                       -8-

<PAGE>

expressly  provided in the Indenture,  no payment or adjustment shall be made on
account of interest  accrued on this Security (or portion  thereof) so converted
or on account of any  dividend or  distribution  on any such Common Stock issued
upon conversion, but the Holder of record of this Security on January 31 or July
31 shall be entitled  to receive  interest  on such  Security on the  succeeding
February 15 or August 15  notwithstanding  the conversion of such Security prior
to such  February 15 or August 15. If so required by the Issuer or the  Trustee,
this  Security,  upon  surrender  for  conversion  as  aforesaid,  shall be duly
endorsed by, or be accompanied by instruments of transfer,  in form satisfactory
to the Issuer, duly executed by, the Holder or by his duly authorized  attorney.
The  conversion  price from time to time in effect is subject to  adjustment  as
provided in the Indenture.  No fractions of shares will be issued on conversion.
In the sole discretion of the Board of Directors, any fractional interest may be
rounded up to the nearest full share,  or an adjustment in cash will be made for
any fractional  interest,  in either case in accordance  with and as provided in
the Indenture.

                  No reference  herein to the Indenture and no provision of this
Security or of the Indenture shall alter or impair the obligation of the Issuer,
which is absolute and  unconditional,  to pay the  principal of and premium,  if
any, and interest on this  Security at the place,  times,  and rate,  and in the
currency, herein prescribed.

                  The  Securities  are issuable  only as  registered  Securities
without coupons in denominations of $1,000 and any integral multiple of $1,000.

                  In the manner and subject to the  limitations  provided in the
Indenture,  this Security may be exchanged for a like aggregate principal amount
of Securities of other authorized denominations.

                  Upon due  presentment  for  registration  of  transfer of this
Security at the  above-mentioned  office or agency of the Issuer, a new Security
or  Securities  of  authorized  denominations,  for a like  aggregate  principal
amount,  will

                                       -9-

<PAGE>

be issued to the  transferee  as provided in the  Indenture.  No service  charge
shall be made for any such transfer, but the Issuer may require payment of a sum
sufficient to cover any tax or other governmental  charge that may be imposed in
relation thereto.

                  The  Securities may be redeemed at the option of the Issuer as
a whole,  or from time to time in part,  on and after  February 20,  2003,  upon
mailing a notice of such redemption not less than 20 nor more than 60 days prior
to the date fixed for  redemption  to the Holders of  Securities to be redeemed,
all as provided in the Indenture,  at the following redemption prices (expressed
in  percentages  of the  principal  amount)  together in each case with  accrued
interest to the date fixed for redemption:  If rendered during the  twelve-month
period beginning February 15, of each year indicated,

         Year                                           Redemption Price

         February 20, 2003                                   102.50%
         February 15, 2004                                   101.67
         February 15, 2005                                   100.83
         February 15, 2006 and thereafter                    100.00

                  The  Securities  do not have the benefit of any  sinking  fund
obligations.

                  If at any time  there  shall  occur any  Change in  Control as
defined in the Indenture  with respect to the Issuer,  each Holder of Securities
shall,  except as otherwise  provided in the Indenture,  have the right, at such
Holder's  option but subject to the conditions  set forth in the  Indenture,  to
require the Issuer to redeem on the Change in Control Repurchase Date as defined
in the Indenture all or any part of such Holder's  Securities  that is $1,000 or
an integral  multiple  thereof at a Change in Control  Repurchase Price equal to
the principal amount thereof, and accrued and unpaid interest, if any, up to but
excluding the Change in Control Repurchase Date.

                                      -10-

<PAGE>

                  Subject to  payment by the Issuer of a sum suffi  cient to pay
the amount due on  redemption,  interest on this Security (or portion  hereof if
this  Security  is  redeemed  in part)  shall cease to accrue upon the date duly
fixed for  redemption  of this  Security (or portion  hereof if this Security is
redeemed in part).

                  Subject  to the terms and  conditions  of the  Indenture,  the
Issuer shall become  obligated  to  purchase,  at the option of the Holder,  the
Securities held by such Holder on February 20, 2007 (the  "Repurchase  Date") at
the Repurchase Price of 100% of the principal  amount thereof,  plus accrued and
unpaid interest,  if any, up to but excluding the Repurchase Date, upon delivery
of a Repurchase Notice containing the information set forth in the Indenture, at
any time from the opening of business on the date that is 20 Business Days prior
to the Repurchase  Date until the close of business on the  Repurchase  Date and
upon  delivery of the  Securities to the Paying Agent by the Holder as set forth
in the Indenture.

                  The Repurchase Price may be paid, at the option of the Issuer,
in cash or by the issuance and delivery of shares of Class A Common Stock of the
Issuer, or in any combination thereof.

                  Holders  have the right to withdraw any  Repurchase  Notice by
delivering to the Paying Agent a written notice of withdrawal in accordance with
the provisions of the Indenture.

                  If cash (and/or  securities if permitted  under the Indenture)
sufficient to pay the Repurchase  Price of all Securities or portions thereof to
be  purchased as of the  Repurchase  Date,  is  deposited  with the Trustee or a
Paying  Agent  on the  Repurchase  Date,  interest  ceases  to  accrue  on  such
Securities (or portions thereof) immediately after such Repurchase Date, and the
Holder  thereof  shall  have no other  rights as such  (other  than the right to
receive the Repurchase Price upon surrender of such Security).

                                      -11-

<PAGE>

                  The  Holder  of this  Security  and the  Class A Common  Stock
issuable on the conversion  hereof is entitled to the benefits of a Registration
Rights  Agreement  executed by the Issuer.  Whenever in this Security there is a
reference  to the  payment of interest  on, or in respect  of, a Security,  such
mention shall be deemed to include mention of the payment of liquidated  damages
to the extent payable as contemplated in such Registration Rights Agreement.

                  The Issuer, the Trustee and any authorized agent of the Issuer
or the Trustee may deem and treat the  registered  Holder hereof as the absolute
owner of this  Security  (whether  or not this  Security  shall be  overdue  and
notwithstanding any notation of ownership or other writing hereon made by anyone
other than the Issuer or the  Trustee or any  authorized  agent of the Issuer or
the  Trustee),  for the purpose of  receiving  payment of, or on account of, the
principal hereof and premium, if any, and, subject to the provisions on the face
hereof,  interest hereon and for all other purposes,  and neither the Issuer nor
the  Trustee  nor any  authorized  agent of the Issuer or the  Trustee  shall be
affected by any notice to the contrary.

                  No recourse  shall be had for the payment of the  principal of
or  premium,  if any,  or the  interest  on this  Security,  for any claim based
hereon,  or  otherwise  in  respect  hereof,  or based on or in  respect  of the
Indenture or any indenture  supplemental thereto,  against any incorporator,  as
such, or against any past, present or future  stockholder,  officer or director,
as such,  of the  Issuer or of any  partner  or  member of the  Issuer or of any
successor,  either  directly or through the Issuer or any successor,  whether by
virtue of any constitution,  statute or rule of law or by the enforcement of any
assessment or penalty or otherwise,  all such liability being, by the acceptance
thereof and as part of the consideration for the issue hereof,  expressly waived
and released.

                  The  Indenture  and this  Security  shall be  governed  by and
construed in accordance with the laws of the State of New York.

                                      -12-

<PAGE>

                [FORM OF TRUSTEE'S CERTIFICATE OF AUTHENTICATION]

                  This   is   one   of   the   Securities   described   in   the
within-mentioned Indenture.

                                            THE BANK OF NEW YORK,
                                            as Trustee

                                             ___________________________________
                                                    Authorized Signatory

                                      -13-

<PAGE>

                           [FORM OF CONVERSION NOTICE]

                  To:      American Tower Corporation

                  The undersigned owner of this Security hereby: (i) irrevocably
exercises  the option to convert  this  Security,  or the portion  hereof  below
designated,  for shares of Class A Common Stock of American Tower Corporation in
accordance with the terms of the Indenture referred to in this Security and (ii)
directs  that  such  shares  of  Class  A  Common  Stock  deliverable  upon  the
conversion,  together  with any check in payment for  fractional  shares and any
Security(ies)  representing any unconverted  principal amount hereof,  be issued
and delivered to the  registered  Holder hereof unless a different name has been
indicated below. If shares and/or  Security(ies) are to be delivered  registered
in the name of a person other than the undersigned, the undersigned will pay all
transfer taxes payable with respect  thereto.  Any amount required to be paid by
the undersigned on account of interest accompanies this Security.

Dated:
                                                     ___________________________
                                                              Signature

Fill in for  registration of shares if to be delivered,  and of Securities if to
be issued, otherwise than to and in the name of the registered Holder.

                                                     ___________________________
                                                      Social Security or Other
                                                     Taxpayer Identifying Number

_________________________________________________________
         (Name)

_________________________________________________________
         (Street Address)

_________________________________________________________
         (City, State and Zip Code)
         (Please print name and address)

                                            Principal Amount to Be Converted:
                                                     (if less than all)

                                            $___________________________________

                                      -14-

<PAGE>

                  [FORM OF OPTION OF HOLDER TO ELECT REDEMPTION
                             UPON CHANGE IN CONTROL]

                  If you want to elect to have this  Security  purchased  in its
entirety by the Issuer pursuant to Article Thirteen of the Indenture,  check the
box:

                  |_|

                  If you  want to  elect  to have  only a part of this  Security
purchased by the Issuer pursuant to Article Thirteen of the Indenture, state the
principal amount:
$

Dated:                                      Your Signature:____________________
                                            (Sign exactly as name appears
                                            on the face of this Security)

Signature Guarantee:___________________________________
                    (Signature must be guaranteed by
                    a member firm of the New York Stock
                    Exchange or a commercial bank or
                    trust company)

                                      -15-

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