Document:

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                             AMENDED AND RESTATED

                         REGISTRATION RIGHTS AGREEMENT

                                     AMONG

                          AMERICAN TOWER CORPORATION

                                      and

                         THE STOCKHOLDERS NAMED HEREIN

                               February 25, 1999
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               AMENDED AND RESTATED REGISTRATION RIGHTS AGREEMENT

     This Amended and Restated Registration Rights Agreement (this "Agreement")
is made and entered into as of February 25, 1999, by and among American Tower
Corporation, a Delaware corporation ("ATC"), and the undersigned Persons which
have heretofore agreed to acquire or have acquired the Registrable Securities
(individually a "Stockholder" and collectively the "Stockholders" which term is
further defined in Section 12(a)).

     WHEREAS, American Tower Systems Corporation (now known as American Tower
Corporation) and certain of the Stockholders are parties to a Registration
Rights Agreement, dated as of January 22, 1998 (the "Original Registration
Rights Agreement"); and

     WHEREAS, ATC and the Stockholders desire to amend and restate the Original
Registration Rights Agreement in its entirety to make certain changes to the
Original Registration Rights Agreement; and

     WHEREAS, ATC has entered into and may in the future enter into agreements
pursuant to which it has agreed or will have agreed to issue securities the
holders of which have required or will require registration rights of a nature
set forth in this Agreement;

     NOW, THEREFORE, in consideration of the recitals, the mutual covenants and
agreements herein contained, and other valuable consideration, the receipt,
adequacy and sufficiency of which are hereby acknowledged, the parties hereto,
intending to be legally bound, do hereby covenant and agree as follows:

     1.   Registration of Securities.

     (a)  Registration by ATC.  If at any time or from time to time ATC shall
propose to file on its behalf or on behalf of any of its security holders a
registration statement under the Securities Act with respect to any class of
Common Stock, except in connection with an Excluded Offering, ATC shall, except
to the extent not required to do so pursuant to the provisions of Section 1(d)
or 1(e), in each case:

          (i)    promptly give written notice to each Stockholder at least
     thirty (30) days (or such shorter period as ATC deems reasonable under the
     circumstances) before the anticipated filing date. Such notice shall
     include the anticipated offering price or range thereof and the plan of
     distribution;

          (ii)   include in such registration (and any related qualification
     under blue sky or other state securities laws), and, at the request of a
     Stockholder, in any underwriting involved therein, all Registrable
     Securities specified in a written request or requests, made within ten (10)
     business days after such written notice from ATC, by any Stockholder; and

          (iii)  use its reasonable business efforts to cause the managing
     underwriter or underwriters of any proposed underwritten offering of any
     class of Common Stock to permit the Registrable Securities requested to be
     included in the Registration Statement for such offering on the same terms
     and conditions as the Common Stock of ATC included therein.
     Notwithstanding the foregoing, if the managing underwriters of such
     offering deliver a written opinion to the holders of such Registrable
     Securities that marketing considerations require a limitation on the
     Registrable Securities included in any Registration Statement filed under
     this Section, then, subject to the advice of said managing underwriter or
     underwriters as to the size and composition
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     of the offering, and subject to the provisions of Section 1(d), such
     limitation will be imposed pro rata (based upon the relative proposed
     public offering price of the Registrable Securities proposed to be
     included) among all holders of Registrable Securities who requested
     inclusion in the registration pursuant to this Section.

     If any Stockholder desires to have Registrable Securities registered under
this Section, it shall be required so to advise ATC in writing within ten (10)
business days after the date of ATC's notice, setting forth the number or amount
of Registrable Securities for which registration is so requested.  Neither the
delivery of the notice by ATC nor of the request by any Stockholders shall in
any way obligate ATC to file a Registration Statement and, notwithstanding such
filing, ATC may, at any time prior to the effective date thereof, determine not
to offer the securities to which the registration statement relates without
liability to any of the Stockholders.  No registration of Registrable Securities
effected under this Section shall relieve ATC of its obligation to effect
registration of Registrable Securities upon any request made pursuant to the
provisions of Section 1(b).

     Anything in this Section 1(a) to the contrary notwithstanding, the
provisions of this Section 1(a) shall not apply to any registration statement
filed by ATC under the Securities Act pursuant to the provisions of the CSFB
Agreement.

     (b)  Registration at Stockholders' Request'.  Upon the written request of
any Significant Stockholder requesting that ATC effect the registration under
the Securities Act of all or part of the Registrable Securities held by such
Stockholder, specifying the intended method or methods of disposition of such
Registrable Securities, ATC shall, except to the extent not required to do so
pursuant to the provisions of this Section 1(b) or Section 1(d) or (e), promptly
(and in any event within five (5) business days) give written notice of such
requested registration to all holders of Registrable Securities and thereupon
will expeditiously prepare and, within forty-five (45) days, use its reasonable
business efforts to file under the Securities Act a registration statement and
effect the registration of:

          (i)  the Registrable Securities which ATC has been so requested to
     register by such Stockholders, for disposition in accordance with the
     intended method of disposition stated in such request, and

          (ii) all other Registrable Securities which ATC has been requested to
     register by the holders of Registrable Securities by written request
     delivered to ATC within ten (10) business days after the giving of such
     notice by ATC (which request shall specify the intended method of
     disposition of such Registrable Securities).

     Each registration requested pursuant to this Section shall be effected by
the filing of a Registration Statement on Form S-1 (or such other form as the
Commission may from time to time require in order to effectuate a public
offering of common stock of a company such as ATC and in a method of disposition
such as that proposed), unless the use of a different form has been agreed upon
in writing by holders of not less than a majority in value (based upon the
proposed public offering price) of the Registrable Securities as to which
registration has so been requested.  Notwithstanding the preceding sentence, ATC
need not so cause a Registration Statement so filed pursuant to the provisions
of this Section on a Form S-1 (or any successor form) to become effective under
the Securities Act on more than four (4) occasions, one of which can be
initiated only by or with the consent of Cox; provided, however, that there
shall be no limit on the number of times ATC is obligated to file Registration
Statements on Form S-2 or S-3 (or any successor forms) pursuant to the
provisions of this Section (except as contemplated by the definition of
Significant Stockholder); and provided further, however, that any registration
of Registrable Securities requested by one or more Stockholders pursuant to this
Section

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which shall not have become and remained effective in accordance with the
provisions of Section 1(c) shall not be deemed to be a registration for purposes
of this Section.

     ATC shall not grant to any person the right to request ATC to register, nor
shall ATC include in any registration pursuant to this Section, any securities
other than the Registrable Securities, without the written consent of holders of
not less than a majority in value (based upon the proposed public offering
price) of the Registrable Securities as to which registration has been so
requested.

     Whenever registration requested by one or more Stockholders pursuant to
this Section is for an underwritten offering, only Registrable Securities which
are to be distributed by the underwriters designated by such Stockholders may be
included in such registration, without the written consent of holders of not
less than a majority in value (based upon the proposed public offering price) of
the Registrable Securities as to which registration has been so requested.  If
Stockholders holding not less than a majority in value of the Registrable
Securities (based upon the proposed public offering price) to be included in
such registration shall determine that the number of Registrable Securities
should be limited due to market conditions or otherwise, all holders of
Registrable Securities proposing to sell Registrable Securities in such
underwritten offering shall share pro rata in the number of Registrable
Securities to be excluded from such underwritten offering, such sharing to be
based on the value (based upon the proposed public offering price) of the
respective numbers of Registrable Securities as to which registration has been
requested by such Stockholders.

          (c)  Registration Generally. If and when ATC shall be required by the
provisions of this Section to effect the registration of Registrable Securities
under the Securities Act, ATC will use its reasonable business efforts to effect
such registration to permit the sale of such Registrable Securities in
accordance with the intended method or methods of disposition thereof, and
pursuant thereto it will, subject to the provisions of Section 1(d) and 1(e), as
expeditiously as possible:

          (i)  before filing a Registration Statement or Prospectus or any
     amendments or supplements thereto, furnish to the holders of the
     Registrable Securities covered by such Registration Statement and the
     managing underwriters, if any, copies of all such documents proposed to be
     filed, which documents will be made available, on a timely basis, for
     review by such holders and underwriters, and their respective counsel, and
     ATC will not file any Registration Statement or amendment thereto or any
     Prospectus or any supplement thereto to which the holders of not less than
     a majority in value (based upon the proposed public offering price) of the
     Registrable Securities covered by such Registration Statement or the
     managing underwriters, if any, shall reasonably have objected;

          (ii) prepare and file with the Commission such amendments and post-
     effective amendments to any Registration Statement, and such supplements to
     the Prospectus, as may be reasonably requested by any holder of Registrable
     Securities included in such Registration Statement or any underwriter of
     Registrable Securities or as may be required by the rules, regulations or
     instructions applicable to the registration form utilized by ATC or by the
     Securities Act, the Exchange Act or otherwise necessary to keep such
     Registration Statement effective for the applicable period and cause the
     Prospectus as so supplemented to be filed pursuant to Rule 424 under the
     Securities Act; and comply with the provisions of the Securities Act with
     respect to the disposition of all Registrable Securities covered by such
     Registration Statement during the applicable period in accordance with the
     intended method or methods of disposition by the holders of such
     Registrable Securities set forth in such Registration Statement or
     Prospectus as so supplemented;

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          (iii)  notify the selling holders of Registrable Securities and the
     managing underwriters, if any, promptly, and (if requested by any such
     Person) confirm such advice in writing,

                 (A)  when the Prospectus or any supplement thereto or any
                      amendment or post-effective amendment to the Registration
                      Statement has been filed, and, with respect to the
                      Registration Statement or any post-effective amendment,
                      when the same has become effective,

                 (B)  of any request by the Commission for amendments or post-
                      effective amendments to the Registration Statement or
                      supplements to the Prospectus or for additional
                      information,

                 (C)  of the issuance by the Commission of any stop order
                      suspending the effectiveness of the Registration Statement
                      or the initiation or threatening of any proceeding for
                      such purpose,

                 (D)  if at any time the representations and warranties of ATC
                      contemplated by paragraph (xv) below cease to be true and
                      correct in all material respects,

                 (E)  of the receipt by ATC of any notification with respect to
                      the suspension of the qualification of the Registrable
                      Securities for sale in any jurisdiction or the initiation
                      or threatening of any proceeding for such purpose, and

                 (F)  of the existence of any Event which results in the
                      Registration Statement, the Prospectus or any document
                      incorporated therein by reference containing an untrue
                      statement of material fact or omitting to state a material
                      fact required to be stated therein or necessary to make
                      the statements therein, in light of the circumstances
                      under which they were made, not misleading;

          (iv)   use its reasonable business efforts to obtain the withdrawal of
     any order suspending the effectiveness of the Registration Statement or any
     qualification referred to in paragraphs (iii)(C) and (iii)(E) at the
     earliest possible moment;

          (v)    if requested by the managing underwriters or a holder of
     Registrable Securities being sold in connection with an underwritten
     offering, immediately incorporate in a Prospectus supplement or post-
     effective amendment to the Registration Statement such information as the
     managing underwriters or the holders of not less than a majority in value
     (based upon the proposed public offering price) of the Registrable
     Securities being sold reasonably request to have included therein relating
     to the plan of distribution with respect to such Registrable Securities,
     including, without limitation, information with respect to the amount of
     other Registrable Securities being sold to such underwriters, the purchase
     price being paid therefor by such underwriters and with respect to any
     other terms of the underwritten (or best efforts underwritten) offering of
     the Registrable Securities to be sold in such offering; and make all
     required filings of such Prospectus supplement or post-effective amendment
     promptly after being notified of the matters to be incorporated in such
     Prospectus supplement or post-effective amendment;

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          (vi)   at the request of any selling holder of Registrable Securities,
     furnish to such selling holder of Registrable Securities and each managing
     underwriter, if any, without charge, at least one signed copy of the
     Registration Statement and any post-effective amendment thereto, including
     financial statements and schedules, all documents incorporated therein by
     reference and all exhibits (including those incorporated by reference);

          (vii)  deliver to each selling holder of Registrable Securities and
     the underwriters, if any, without charge, as many copies of the
     Registration Statement, each Prospectus (including each preliminary
     prospectus) and any amendment or supplement thereto (in each case including
     all exhibits, except that ATC shall not be obligated to furnish any such
     selling holder more than two copies of such exhibits other than
     incorporation documents), as such persons may reasonably request, together
     with such documents incorporated by reference in such Registration
     Statement or Prospectus, and such other documents as such selling holder or
     underwriter may reasonably request in order to facilitate the disposition
     of the Registrable Securities covered by such registration statement; ATC
     consents to the use of each Prospectus or any supplement thereto by each
     selling holder of Registrable Securities and the underwriters, if any, in
     connection with the offering and sale of the Registrable Securities covered
     by each Registration Statement or any amendment thereto;

          (viii) prior to any public offering of Registrable Securities, use
     its reasonable business efforts to register or qualify or cooperate with
     the selling holders of Registrable Securities, the underwriters, if any,
     and their respective counsel in connection with the registration or
     qualification of such Registrable Securities for offer and sale under the
     securities or blue sky laws of such jurisdictions as any selling holder or
     underwriter reasonably requests in writing and do any and all other acts or
     things necessary or advisable to enable the disposition in such
     jurisdictions of the Registrable Securities covered by the Registration
     Statement; provided, however, that ATC will not be required to qualify
     generally to do business in any jurisdiction where it is not then so
     qualified or to take any action which would subject it to general service
     of process or general taxation in any such jurisdiction where it is not
     then so subject;

          (ix)   cooperate with the selling holders of Registrable Securities
     and the underwriters, if any, to facilitate the timely preparation and
     delivery of certificates representing Registrable Securities to be sold and
     not bearing any restrictive legends; and enable such Registrable Securities
     to be in such denominations and registered in such names as the
     underwriters may reasonably request at least two (2) business days prior to
     any sale of Registrable Securities to the underwriters;

          (x)    use its reasonable business efforts to cause the Registrable
     Securities covered by the Registration Statement to be registered with or
     approved by such other governmental agencies or authorities as may be
     necessary or advisable to enable the sellers thereof or the underwriters,
     if any, to consummate the disposition of such Registrable Securities;

          (xi)   if any event contemplated by paragraph (iii) (F) above shall
     exist, prepare and furnish to such holders a post-effective amendment to
     the Registration Statement or supplement to the Prospectus or any document
     incorporated therein by reference or file any other required document so
     that, as thereafter delivered to the purchasers of the Registrable
     Securities, the Prospectus will not contain an untrue statement of a
     material fact or omit to state any material fact required to be stated
     therein or necessary to make the statements therein, in light of the
     circumstances under which they were made, not misleading;

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          (xii)  cause all Registrable Securities covered by the Registration
     Statement to be listed on each securities exchange or other trading market
     on which securities of the same class are then listed or traded or, if the
     Registrable Securities are not then listed on a securities exchange, and if
     the NASD is reasonably likely to permit the inclusion of the Registrable
     Securities on NASDAQ, use its reasonable business efforts to facilitate the
     inclusion of the Registrable Securities on NASDAQ;

          (xiii) not later than the effective date of the Registration
     Statement, provide a CUSIP number for all Registrable Securities and
     provide the applicable transfer agent or agents with printed certificates
     or instruments for the Registrable Securities which are in a form eligible
     for deposit with Depository Trust Company or other transferee and otherwise
     meeting the requirements of any securities exchange or other trading market
     on which such Registrable Securities are listed or traded;

          (xiv)  pay all Registration Expenses in connection with any
     registration pursuant to the provisions of this Section.  Without limiting
     the generality of the foregoing, in connection with each Registration
     Statement required hereunder, ATC will reimburse the holders of Registrable
     Securities being registered pursuant to such Registration Statement for the
     reasonable fees and disbursements of not more than one counsel (or more
     than one counsel if a conflict exists among such selling holders in the
     exercise of the reasonable judgment of counsel for the selling holders and
     counsel for ATC, provided that such selling holders shall use their
     reasonable business efforts to minimize conflicts of counsel) chosen by the
     holders of not less than a majority in value (based on the proposed public
     offering price) of the Registrable Securities being sold;

          (xv)   enter into agreements (including underwriting agreements) and
     take all other appropriate actions in order to expedite or facilitate the
     disposition of such Registrable Securities and in such connection, whether
     or not an underwriting agreement is entered into and whether or not the
     offer and sale of the Registrable Securities is an underwritten offering:

                 (A)  make such representations and warranties to the holders of
                      such Registrable Securities and the underwriters, if any,
                      in form, substance and scope, reasonably satisfactory to
                      such holders and underwriters, as are customarily made by
                      issuers to underwriters in primary underwritten offerings;

                 (B)  obtain opinions and updates thereof of counsel which
                      counsel and opinions to ATC (in form, scope and substance)
                      shall be reasonably satisfactory to the underwriters, if
                      any, and the holders of not less than a majority in value
                      (based on the proposed public offering price) of the
                      Registrable Securities being sold, addressed to each
                      selling holder and the underwriters, if any, covering the
                      matters customarily covered in opinions requested in
                      underwritten offerings and such other matters as may be
                      reasonably requested by such holders and underwriters;

                 (C)  obtain so-called "cold comfort" letters and updates
                      thereof from ATC's independent public accountants
                      addressed to the selling holders of Registrable Securities
                      and the underwriters, if any, such letters to be in
                      customary form and covering matters of the type
                      customarily covered in "cold comfort" letters to
                      underwriters in connection with primary underwritten
                      offerings and such other matters as may be reasonably
                      requested by such holders and underwriters;

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                 (D)  if an underwriting agreement is entered into, cause the
                      same to set forth in full the indemnification provisions
                      and procedures of Section 3 (or such other substantially
                      similar provisions and procedures as the underwriters
                      shall reasonably request) with respect to all parties to
                      be indemnified pursuant to said Section; and

                 (E)  deliver such documents and certificates as may be
                      reasonably requested by the holders of not less than a
                      majority in value (based on the proposed public offering
                      price) of the Registrable Securities being sold or the
                      underwriters, if any, to evidence compliance with the
                      provisions of this Section and with any customary
                      conditions contained in the underwriting agreement or
                      other agreement entered into by ATC.

          The requirements of subparagraphs (B), (C) and (D) of this paragraph
          (xv) shall be complied with at the effectiveness of such Registration
          Statement, each closing under any underwriting or similar agreement as
          and to the extent required thereunder and from time to time as may
          reasonably be requested by a majority in value (based on the proposed
          public offering price) of Registrable Securities being sold pursuant
          to such Registration Statement, all in a manner consistent with
          customary industry practice;

          (xvi)   make available to a representative of the holders of not less
     than a majority in value (based on the proposed public offering price) of
     the Registrable Securities, any underwriter participating in any
     disposition pursuant to such Registration Statement, and any attorney or
     accountant retained by such holders or underwriter, all  financial,
     corporate and other records and documents of ATC, and cause ATC's officers,
     directors and employees to supply all information reasonably requested by
     any such representatives, underwriter, attorney or accountant in connection
     with the registration, with respect to each at such time or times as the
     person requesting such information shall reasonably determine; provided,
     however, that any records, information or documents that are designated by
     ATC in writing as confidential shall be kept confidential by such persons
     unless disclosure of such records, information or documents is required by
     court or administrative order or applicable law or otherwise becomes public
     without breach of the provisions of this paragraph;

          (xvii)  otherwise use its reasonable business efforts to comply with
     the Securities Act, the Exchange Act, all applicable rules and regulations
     of the Commission and all applicable state blue sky and other securities
     laws, rules and regulations, and make generally available to its security
     holders, earnings statements satisfying the provisions of Section 11(a) of
     the Securities Act, no later than thirty (30) days after the end of any 12-
     month period (or ninety (90) days if the end of such 12-month period
     coincides with the end of a fiscal quarter or fiscal year, respectively) of
     ATC (A) commencing at the end of any month in which Registrable Securities
     are sold to underwriters in an underwritten offering, or, if not sold to
     underwriters in such an offering, (B) beginning with the first month
     commencing after the effective date of the Registration Statement, which
     statements shall cover said 12-month periods;

          (xviii) cooperate and assist in any filings required to be made with
     the NASD and in the performance of any due diligence investigation by any
     underwriter (including any "qualified independent underwriter" that is
     required to be retained in accordance with the rules and regulations of the
     NASD);

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          (xix)  promptly prior to the filing of any document which is to be
     incorporated by reference into the Registration Statement or the Prospectus
     (after the initial filing of the Registration Statement) provide copies of
     such document to the selling holders of Registrable Securities, the
     underwriters, if any, and their respective counsel, make ATC's
     representatives available for discussion of such document with such persons
     and make such changes in such document prior to the filing thereof as any
     such persons may reasonably request; and

          (xx)   cooperate and assist in any filings required to be made with
     the FCC, including without limitation the obtaining of any consents of the
     FCC required in connection with any change in control of ATC.

          (d)    Restrictions on Registration.  Anything in Section 1 to the
contrary notwithstanding, ATC shall not be required to register Registrable
Securities on behalf of any Stockholder to the following extent and subject to
the following conditions:  in the case of any registration initially proposed to
be filed solely on behalf of ATC if, in the opinion of the managing underwriters
of the proposed public offering (a copy of which opinion shall have been
furnished to any Stockholder requesting registration (or each such holder if ATC
has elected not to notify the holders of Registrable Securities pursuant to the
provisions of Section 1(a) because it is not required to include any Registrable
Securities in such registration pursuant to the provisions of this Section)),
such registration (or such portion thereof as may be specified in such opinion)
would adversely affect the proposed public offering price or the plan of
distribution contemplated by the proposed ATC offering, in which event ATC shall
(unless in the opinion of such managing underwriters (a copy of which shall be
similarly furnished) to do so would materially and adversely affect the proposed
public offering price or such plan of distribution)) cause such Registration
Statement to remain in effect and to be phrased in such a manner so that the
Stockholders requesting registration thereunder may, during a period commencing
not less than sixty (60) days or more than ninety (90) days (or such other
period as such managing underwriters may approve as not so adversely affecting
the proposed public offering price or such plan of distribution) after the
closing of the sale to the underwriters pursuant to the original distribution
thereunder, offer and sell under such Registration Statement the Registrable
Securities referred to in the request of registration pursuant to this Section
1.

     (e)  Additional Restrictions on Registration. Anything in this Agreement to
the contrary notwithstanding, ATC shall not be required to file a registration
statement requested pursuant to this Section 1 if ATC has furnished, to the
Stockholders requesting a registration statement to be filed, a certificate
signed by the Chief Executive Officer or the Chief Financial Officer of ATC
stating that in the good faith judgment of the signer of such certificate the
filing of a registration statement would require the disclosure of material
information that ATC has a bona fide business purpose for preserving as
confidential and that is not then otherwise required to be disclosed; provided,
however, that ATC's obligation to use its reasonable business efforts to effect
a registration pursuant to this Section 1 may not be deferred pursuant to this
paragraph (e) for more than ninety (90) days from the date of receipt of a
written request from such Stockholders, and provided further, however, that ATC
shall not utilize this right more than once during any twelve (12) month period
unless the Stockholders requesting such registration have been afforded a
reasonable period (not less than ninety (90) days) during such twelve (12) month
period to effect such registration.

     2.   Conditions to Registration.
          --------------------------

     Each Stockholder's right to have Registrable Securities included in any
Registration Statement filed by ATC in accordance with the provisions of Section
1 shall be subject to the following conditions:

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          (a) The holders on whose behalf such Registrable Securities are to be
     included shall be required to furnish ATC in a timely manner with all
     information required by the applicable rules and regulations of the
     Commission concerning the proposed method of sale or other disposition of
     such Registrable Securities, the identity of and compensation to be paid to
     any proposed underwriters to be employed in connection therewith, and such
     other information as may be reasonably requested by ATC or its counsel
     properly to prepare and file such Registration Statement in accordance with
     applicable provisions of the Securities Act;

          (b) If any such holder desires to sell and distribute Registrable
     Securities over a period of time, or from time to time, at then prevailing
     market prices, then any such holder shall execute and deliver to ATC such
     written undertakings as ATC and its counsel may reasonably request in order
     to assure full compliance with applicable provisions of the Securities Act
     and the Exchange Act;

          (c) In the case of any underwritten offering on behalf of the holders
     of Registrable Securities pursuant to the provisions of Section 1(b), the
     managing underwriters shall be subject to the approval of ATC, such
     approval not to be unreasonably withheld, delayed or conditioned;

          (d) In the case of any registration requested pursuant to the
     provisions of Section 1(a), the offering price for any Registrable
     Securities to be so registered shall be no less than for any securities of
     the same class then to be registered for sale for the account of ATC or
     other security holders, unless such Registrable Securities are to be
     offered from time to time based on the prevailing market price;

          (e) Upon receipt of any notice from ATC of the existence of any event
     of the nature referred to in paragraph (iii) of Section 1(c), such holder
     will forthwith discontinue disposition of Registrable Securities until such
     holders receipt of the copies of the supplemented or amended Prospectus
     contemplated by such paragraph, or until it is advised in writing by ATC
     that the use of the Prospectus may be resumed, and has received copies of
     any additional or supplemental filings which are incorporated by reference
     in the Prospectus, and, if so directed by ATC, such holder will deliver to
     ATC (at its expense) all copies, other than permanent file copies then in
     such holder's possession, of the Prospectus covering such Registrable
     Securities current at the time of receipt of such notice; and

          (f) In the event any filing with or consent of the FCC is required,
     cooperate and assist in any such filings, including without limitation
     providing all information required in obtaining any consents of the FCC
     required in connection with any change in control of ATC.

     3.   Indemnification.
          ---------------

     (a)  Indemnification by ATC.  In the event of the registration of any
Registrable Securities under the Securities Act pursuant to the provisions
hereof, ATC will, to the extent permitted by Applicable Law, indemnify and hold
harmless each Stockholder on whose behalf such Registrable Securities shall have
been registered, its partners, trustees, advisory committee members, directors,
officers, employees, representatives and agents, each underwriter, broker and
dealer, if any, who participates in the offering or sale of such Registrable
Securities, and each other Person, if any, who controls such Stockholder or any
such underwriter, broker or dealer within the meaning of the Securities Act or
the Exchange Act (each such person being hereinafter sometimes referred to as an
"indemnified person"), from and against any Claims, joint or several, to which
such indemnified person may become subject, including without limitation under
the Securities Act, the Exchange Act or any state securities or blue sky law,
insofar as such Claims arise out of or are based upon any untrue statement or
alleged untrue

                                     -10-
<PAGE>

statement of any material fact contained or incorporated by reference in any
Registration Statement or Prospectus or any amendment or supplement thereto or
in any preliminary prospectus, or any document incorporated by reference
therein, or arise out of or based upon the omission or alleged omission to state
therein a material fact required to be stated therein or necessary to make the
statements therein, in light of the circumstances under which they were made,
not misleading, and will reimburse each such indemnified person for any legal or
any other expenses reasonably incurred by such indemnified person in connection
with investigating or defending, settling or satisfying any such Claim;
provided, however, that ATC will not be liable in any such case to the extent
that any such Claim arises out of or is based upon an untrue statement or
alleged untrue statement or omission or alleged omission made or incorporated by
reference in the Registration Statement, Prospectus, amendment or supplement in
reliance upon and in conformity with written information furnished to ATC by
such indemnified person specifically stating that it is for use in preparation
thereof. Such indemnity shall remain in full force and effect regardless of any
investigation made by or on behalf of such indemnified person and shall survive
the transfer of such Registrable Securities by such Stockholder

     (b) Indemnification by Holders of Registrable Securities.  In the event of
the registration of any Registrable Securities under the Securities Act pursuant
to the provisions hereof, each Stockholder on whose behalf such Registrable
Securities shall have been registered will, to the extent permitted by
Applicable Law, severally but not jointly, indemnify and hold harmless, ATC,
each director of ATC, each officer of ATC who signs the registration statement,
each underwriter, broker and dealer, if any, who participates in the offering
and sale of such Registrable Securities and each other Person, if any, who
controls ATC or any such underwriter, broker or dealer within the meaning of the
Securities Act or the Exchange Act (each such person including without
limitation ATC being hereinafter sometimes referred to as an "indemnified
person"), against any Claims, joint or several, to which such indemnified person
may become subject, including without limitation under the Securities Act, the
Exchange Act or any state securities or blue sky law, insofar as such Claims
arise out of or are based upon any untrue statement or alleged untrue statement
of a material fact contained or incorporated by reference in any Registration
Statement or Prospectus or any amendment or supplement thereto or any document
incorporated by reference therein, or arise out of or are based upon the
omission or alleged omission to state therein a material fact required to be
stated therein or necessary to make the statements therein, in light of the
circumstances under which they were made, not misleading, provided that such
untrue statement or alleged untrue statement or omission or alleged omission has
been made or incorporated therein in reliance upon and in conformity with
written information furnished to ATC by such Stockholder specifically stating
that it is for use in preparation thereof, and will reimburse each such
indemnified person for any legal or any other expenses reasonably incurred by
ATC or such indemnified person in connection with investigating or defending,
settling or satisfying any such Claim.  Such indemnity shall remain in full
force and effect regardless of any investigation made by or on behalf of such
indemnified person and shall survive the transfer of such Registrable Securities
by such Stockholder.  In no event shall the liability of any such Stockholder
hereunder be greater in amount than the dollar amount of the proceeds received
by such Stockholder upon the sale of the Registrable Securities giving rise to
such indemnification obligation.

     (c) Procedure.  Promptly after receipt by an indemnified party of notice of
the commencement of any action (including any governmental investigation or
inquiry), such indemnified party will, if a claim in respect thereof is to be
made against an indemnifying party, give written notice to such indemnifying
party of the commencement thereof, but the omission so to notify the
indemnifying party will not relieve it from any liability which it may have to
any indemnified party otherwise than pursuant to the provisions of this Section
and then only to the extent such indemnifying party has been prejudiced, or
otherwise adversely affected thereby and in no event shall such failure relieve
the indemnifying party from any other liability which it may have to the
indemnified party.  In case any such

                                     -10-
<PAGE>

action is brought against any indemnified party, and it notifies an indemnifying
party of the commencement thereof, the indemnifying party will be entitled to
participate in, and to the extent that it may wish, jointly with any other
indemnifying party similarly notified, to assume the defense thereof, with
counsel reasonably satisfactory to such indemnified party, and after notice from
the indemnifying party to such indemnified party, the indemnifying party shall
not, except as hereinafter provided, be responsible for any legal or other
expenses subsequently incurred by such indemnified party in connection with the
defense thereof, other than reasonable cost of investigation. No indemnifying
party will consent to entry of any judgment or enter into any settlement which
does not include as an unconditional term thereof the giving by the claimant or
plaintiff to such indemnified party of a release from all liability in respect
to such Claim.

     Such indemnified party shall have the right to employ separate counsel in
any such action and to participate in the defense thereof, but the fees and
expenses of such counsel shall be the expense of such indemnified party, unless
(i) the indemnifying party has agreed to pay such fees and expenses, (ii) the
indemnifying party shall have failed to assume the defense of such action or
proceeding or has failed to employ counsel reasonably satisfactory to such
indemnified party in any such action or proceeding, or (iii) the named parties
to any such action or proceeding (including any impleaded parties) include both
such indemnified party and the indemnifying party, and such indemnified party
shall have been advised in writing by counsel that representation of both
parties by the same counsel would be inappropriate due to actual or potential
material differing interests between them (in which case, if such indemnified
party notifies the indemnifying party in writing that it elects to employ
separate counsel at the expense of the indemnifying party, the indemnifying
party shall not have the right to assume the defense of such action or
proceeding on behalf of such indemnified party, it being understood, however,
that the indemnifying party shall not, in connection with any one such action or
proceeding or separate but substantially similar or related actions or
proceedings in the same jurisdiction arising out of the same general allegations
or circumstances, be liable for the fees and expenses of more than one separate
firm of attorneys at any time for such indemnified party and any other
indemnified parties, which firm shall be designated in writing by such
indemnified parties).  The indemnifying party shall not be liable for any
settlement of any such action or proceeding effected without its written
consent, but if settled with its written consent, or if there be a final
judgment for the plaintiff in any such action or proceeding, the indemnifying
party agrees to indemnify and hold harmless such indemnified parties from and
against any loss or liability by reason of such settlement or judgment.

     (d) Contribution.  If the indemnification provided for in this Section or
in Section 4 is unavailable, because prohibited or restricted by Applicable Law,
to a party that would have been an indemnified party under either such Section
in respect of any Claims referred to therein, then each party that would have
been an indemnifying party thereunder shall, in lieu of indemnifying such
indemnified party, contribute to the amount paid or payable by such indemnified
party as a result of such Claims in such proportion as is appropriate to reflect
the relative fault of the indemnifying party on the one hand and such
indemnified party on the other in connection with the statement or omission
which resulted in such Claims, as well as any other relevant equitable
considerations.  The relative fault shall be determined by reference to, among
other things, whether the untrue or alleged untrue statement of a material fact
or the omission or alleged omission to state a material fact relates to
information supplied by the indemnifying party or such indemnified party and the
parties' relative intent, knowledge, access to information and opportunity to
correct or prevent such statement or omission.  Notwithstanding the provisions
of this Section, a holder of Registrable Securities shall not, as an indemnified
party, be required to contribute any amount in excess of the amount by which the
total price at which the Registrable Securities sold by such indemnified party
or its Affiliates and distributed to the public were offered to the public
exceeds the amount of any damages which such indemnified party or its Affiliates
have otherwise been required to pay by reason of such untrue or alleged untrue
statement or omission or alleged omission.  ATC and each

                                     -11-
<PAGE>

holder of Registrable Securities agrees that it would not be just and equitable
if contribution pursuant to this Section were determined by pro rata allocation
or by any other method of allocation which does not take account of the
equitable considerations referred to above in this Section. The amount paid or
payable by an indemnified party as a result of the Claims referred to above in
this Section or Section 4 shall include any legal or other expenses reasonably
incurred by such indemnified party in connection with investigation or defending
any such action or claim (which shall be limited as provided in Section 3(c) if
the indemnifying party has assumed the defense of any such action in accordance
with the provisions thereof). The obligations of each Stockholder under this
Section 3(d) are several and not joint.

     No person guilty of fraudulent misrepresentation (within the meaning of
Section 11(f) of the Securities Act) shall be entitled to contribution from any
person who was not guilty of such fraudulent misrepresentation.

     Indemnification or, if appropriate, contribution, similar to that specified
in the preceding provisions of this Section (with appropriate modifications)
shall be given by ATC and each seller of Registrable Securities with respect to
any required registration or other qualification of Registrable Securities under
any Applicable Law other than the Securities Act.

     In the event of any underwritten offering of Registrable Securities under
the Securities Act pursuant to the provisions of Section 1, ATC and each
Stockholder on whose behalf Registrable Securities shall have been registered
agree to enter into an underwriting agreement, in standard form, with the
underwriters, which underwriting agreement may contain additional provisions
with respect to indemnification and contribution in lieu of the provisions of
this Section.

     4.   Exchange Act Registration.
          -------------------------

     ATC covenants and agrees that, at its expense, until such time as the
Stockholders no longer hold any Registrable Securities:

          (a) it will, if required by law, maintain a registration statement
     (containing such information and documents as the Commission shall specify)
     with respect to the Common Stock of ATC under Section 12(b) or 12(g) of the
     Exchange Act effective and will file on time such information, documents
     and reports as the Commission may require or prescribe for companies whose
     stock has been registered pursuant to said Section 12(b) or 12(g);

          (b) it will, if a registration statement with respect to the Common
     Stock of ATC under Section 12(b) or Section 12(g) is effective, upon the
     request of any Stockholder, make whatever other filings with the Commission
     or otherwise make generally available to the public such financial and
     other information as any Stockholder may deem necessary or advisable in
     order to enable him to be permitted to sell shares of Common Stock pursuant
     to the provisions of Rule 144 promulgated under the Securities Act (or any
     successor rule or regulation thereto or any statute hereafter adopted to
     replace or to establish the exemption that is now covered by said Rule
     144);

          (c) it will, if not subject to Section 13 to 15(d) of the Exchange
     Act, upon the request of any Significant Stockholder made on or after
     December 31, 1998, make publicly available the information specified in
     subparagraph (c)(2) of said Rule 144, and will take such further action as
     any Stockholder may reasonably request, all to the extent required from
     time to time to enable such Stockholder to sell Registrable Securities
     without registration under the Securities Act within the limitation of the
     exemptions provided by said Rule 144 (or any successor rule or

                                     -12-
<PAGE>

     regulation to either thereof or any statute hereafter adopted to replace or
     to establish the exemption that is now covered by said Rule 144); and

          (d) it will, if not subject to Section 13 to 15(d) of the Exchange
     Act, upon the request of any Stockholder agree to furnish to a prospective
     purchaser (subject to the execution by it of a confidentiality agreement in
     form, scope and substance reasonably satisfactory to ATC) the information
     specified in subparagraph (d)(4) of Rule 144A promulgated under the
     Securities Act (or any successor rule or regulation thereto or any statute
     hereafter adopted to replace or to establish the exemption that is now
     covered by said Rule 144A), and will take such further action as any
     Stockholder may reasonably request, all to the extent required from time to
     time to enable such Stockholder to sell Registrable Securities without
     registration under the Securities Act within the limitation of the
     exemptions provided by said Rule 144A (or any successor rule or regulation
     thereto or any statute hereafter adopted to replace or to establish the
     exemption that is now covered by said Rule 144A); and

          (e) upon the request of any Stockholder, it will deliver to such
     Stockholder a written statement as to whether it has complied with the
     requirements of this Section.

     ATC represents and warrants that any such registration statement or any
information, documents or report filed with the Commission in connection
therewith or any information so made public shall not contain any untrue
statement of a material fact or omit to state a material fact required to be
stated therein or necessary in order to make the statements contained therein,
in light of the circumstances under which they were made, not misleading.  ATC
shall, to the extent permitted by Applicable Law, indemnify and hold harmless
(or to the extent the same is not enforceable, make contribution to) the
Stockholders, their partners, trustees, advisory committee members, officers,
directors, employees, representatives and agents, each broker, dealer or
underwriter (within the meaning of the Securities Act) acting for any
Stockholder in connection with any offering or sale by such Stockholder of
Registrable Securities or any person, firm or corporation controlling (within
the meaning of Section 15 of the Securities Act or Section 20 of the Exchange
Act) such Stockholder or any such broker, dealer or underwriter from and against
any and all Claims arising out of or resulting from any breach of the foregoing
representation or warranty, all on terms and conditions comparable to those set
forth in Section 3; provided, however, that ATC shall be given written notice
and an opportunity to participate in, and, to the extent that it may wish, to
assume on terms and conditions comparable to those set forth in Section 3, the
defense thereof.

     5.   Termination of Registration Obligations.

     The obligations of ATC to any Stockholder with respect to its rights of
registration provided for in Section 1:

          (a) shall continue until such time as Sullivan & Worcester LLP, or
     other counsel for ATC knowledgeable in securities law matters and
     reasonably acceptable to such Stockholder has delivered a written opinion
     to ATC and such Stockholder to the effect that either (i) such Stockholder
     has no further obligation to comply with the registration requirements of
     the Securities Act or to deliver a prospectus meeting the requirements of
     Section 10(a)(3) of the Securities Act in connection with further sales by
     such Stockholder of Registrable Securities or (ii) such Stockholder is able
     to sell all of the Registrable Securities owned by him pursuant to the
     provisions of Rule 144 under the Securities Act in a three-month period;
     and

          (b) shall not apply to any proposed sales or other dispositions or
     offers therefor of any Registrable Securities with respect to which
     Sullivan & Worcester LLP, or other counsel for ATC knowledgeable in
     securities law matters and reasonably acceptable to such Stockholder has

                                     -13-
<PAGE>

     delivered a written opinion to ATC and the Stockholder proposing to make
     such offer, sale or other disposition to the effect that such Stockholder
     has no obligation to comply with the registration requirements of the
     Securities Act or to deliver a prospectus meeting the requirements of
     Section 10(a)(3) of the Securities Act.

     Any such opinion (a copy of which shall be addressed to such Stockholder)
shall be reasonably satisfactory (in the case of such opinion as to form, scope
and substance) to such Stockholder.

     ATC shall, to the extent permitted by Applicable Law, indemnify and hold
harmless each Stockholder, its partners, trustees, advisory committee members,
officers, directors, employees, representatives and agents and each person, if
any, who controls such Stockholder within the meaning of either Section 15 of
the Securities Act or Section 20 of the Exchange Act, against any Claims to
which such Stockholder, or such partners, trustees, advisory committee members,
officers, directors, employees, representatives and agents or controlling
persons may become subject under the Securities Act, the Exchange Act or
otherwise, insofar as such Claims arise out of or are based upon the failure to
register the Registrable Securities because of the invocation by ATC of the
provisions of this Section under the Securities Act, all on terms and conditions
comparable to those set forth in Section 3; provided, however, that ATC shall be
given written notice and an opportunity to participate in, and to the extent
that it may wish, to assume, on terms and conditions comparable to those set
forth in Section 3, the defense thereof.

     The indemnification and contributions provisions of Sections 3 and 4 and
this Section, and the obligations of each Stockholder pursuant to the provisions
of Section 9, shall survive any termination of ATC's obligations pursuant to
this Section.

     6.   Registration Rights of Others.

     ATC represents and warrants that it has not previously entered into any
agreement with respect to its securities granting any registration rights to any
Person.

     7.   Mergers, etc.
          ------------

     In addition to any other restrictions on mergers, consolidations and
reorganizations contained in the Restated Certificate of Incorporation, by-laws
or agreements of ATC, ATC covenants and agrees that it shall not, directly or
indirectly, enter into any merger, consolidation, sale of all or substantially
all of its assets or business, liquidation, dissolution or reorganization in
which ATC shall not be the surviving corporation unless the surviving
corporation shall, prior to such merger, consolidation or reorganization, agree
in a writing to assume all of the obligations of ATC under this Agreement, and
for that purpose references hereunder to "Registrable Securities" shall be
deemed to include the securities which such holders would be entitled to receive
in exchange for Registrable Securities pursuant to any such merger,
consolidation, sale of all or substantially all of its assets or business,
liquidation, dissolution or reorganization.

     8.   Annual and Quarterly Reports; Other Information.

     ATC will deliver to each Stockholder so long as such Stockholder holds any
Registrable Securities:

          (a) as soon as practicable after the end of each fiscal year and each
     quarter, audited annual and unaudited consolidated quarterly financial
     statements of ATC, including a consolidated balance sheet, a consolidated
     statement of operations, and a consolidated statement

                                     -14-
<PAGE>

     of cash flow, for such year or quarter, all prepared in accordance with
     generally accepted accounting principles;

          (b) as soon as available, copies of all documents filed with the
     Commission; and

          (c) such other financial and other information as may, from time to
     time, be reasonably requested by any Significant Stockholder.

     9.   Lock-Up Agreement.
          -----------------

     Each Stockholder (other than any Stockholder who is not a director and
owns, at such time, 2% or less of all of the Common Stock) agrees that, if
required in connection with the contemplated offering by the managing
underwriter, (a) it and the Restricted Securities shall be bound by any "lock-
up" or other agreement between ATC and any underwriter of Common Stock (or other
equity securities of ATC) which may be entered into in connection with each
underwritten public offering of the Common Stock (or other equity securities of
ATC) so long as the "lock-up" period does not exceed ninety (90) days (or such
longer period (not exceeding one hundred and eighty (180) days) in connection
with the initial underwritten public offering of Class A Common Stock as the
managing underwriters shall have requested) following the commencement of the
public offering, and (b) it will execute such agreements or other documents as
may be reasonably requested by any such underwriter in order to evidence its
agreement set forth in this Section.

     10.  Withdrawals.
          -----------

     Any Stockholder may at any time withdraw any request made pursuant to
Section 1 for registration of its Registrable Securities; provided, however,
that to the extent that such withdrawal or withdrawals result in a termination
of any offering proposed to be made pursuant to Section 1, ATC shall be deemed
to have consummated such offering for purposes of Section 1 unless such
Stockholder(s) agree to reimburse ATC for all Registration Expenses incurred by
ATC in connection with such terminated offering.  Notwithstanding anything in
the foregoing provisions of this Section to the contrary, the provisions of this
Section shall not be applicable in the event that any such withdrawal or
withdrawals resulting in such termination is or are effected on account of (a)
ATC's failure to disclose any material fact required to be disclosed in the
registration statement or any prospectus relating to such offering or (b) any
material adverse change in ATC, its business, assets or condition (financial or
other).

     11.  Definitions.
          -----------

     As used herein, unless the context otherwise requires, the terms (or any
variant in the form thereof) set forth in this Agreement shall have the
respective meanings so set forth.  Terms defined in the singular shall have a
comparable meaning when used in the plural, and vice versa, and the reference to
any gender shall be deemed to include all genders.  Unless otherwise defined or
the context otherwise clearly requires, terms for which meanings are provided in
this Agreement shall have such meanings when used in each agreement, notice,
certificate, communication, opinion or other document executed or required to be
executed pursuant hereto or thereto or otherwise delivered, from time to time,
pursuant hereto or thereto.

     "AFFILIATE" of any Person shall mean any Person which, directly or
indirectly, owns or controls, is under common ownership or control with, or is
owned or controlled by, such Person.  A Person shall be deemed to be "controlled
by" any other Person if such other Person possesses, directly or indirectly,
power to direct or cause the direction of the management or policies of such
Person or the disposition of

                                     -15-
<PAGE>

its assets or property, whether by stock, equity or other ownership, contract,
arrangement or understanding, or otherwise.

     "AGREEMENT" is defined in the first paragraph.

     "APPLICABLE LAW" shall mean any Law of any Authority, whether domestic or
foreign, including without limitation all federal and state Laws, to which the
Person in question is subject or by which it or any of its business or
operations is subject or any of its property is bound.

     "ARS" shall mean American Radio Systems Corporation, a Delaware
corporation.

     "ARS AGREEMENT" shall mean the Registration Rights Agreement, dated as of
November 1, 1993 by and among ARS and certain of the Stockholders named therein,
as amended and restated by the Original Registration Rights Agreement.

     "ARS MERGER AGREEMENT" shall mean the Agreement and Plan of Merger, dated
as of September 19, 1997, as amended and restated as of December 18, 1997, by
and among ARS, CBS Corporation (formerly, Westinghouse Electric Corporation) and
R Acquisition Corp.

     "ATC" is defined in the first paragraph.

     "ATC STOCK PURCHASE AGREEMENT" shall mean the Stock Purchase Agreement,
dated as of January 8, 1998, by and between ATC and certain of the Stockholders
named therein.

     "AUTHORITY" shall mean any governmental or quasi-governmental authority,
whether executive, legislative, judicial, administrative or other, or any
combination thereof, including without limitation any federal, state,
territorial, county, municipal or other government or governmental or quasi-
governmental agency, arbitrator, board, body, branch, bureau or comparable
agency or Entity, commission, corporation, court, department, instrumentality,
mediator, panel, system or other political unit or subdivision or other Entity
of any of the foregoing, whether domestic or foreign.

     "CLAIMS" shall mean, with respect to any Person, any and all debts,
liabilities, obligations, losses, damages, deficiencies,  assessments and
penalties of or against such Person, together with all Legal Actions, pending or
threatened, claims and judgments of whatever kind and nature relating thereto,
and all fees, costs, expenses and disbursements (including without limitation
reasonable attorneys' and other legal fees, costs and expenses) relating to any
of the foregoing.

     "COMMON STOCK", "CLASS A COMMON", "CLASS B COMMON" or "CLASS C COMMON",
shall mean those respective securities described in the Restated Certificate of
Incorporation of ATC.

     "COMMISSION" shall mean the Securities and Exchange Commission or any
successor Authority.

     "COX" shall mean Cox Telecom Towers, Inc., a Delaware corporation, and
shall include any Affiliate of Cox to whom it shall have transferred Registrable
Securities in a transaction not involving a registration of such securities
under the Securities Act.

     "CSFB AGREEMENT" shall mean the registration rights agreement, dated as of
February 4, 1999, by and between ATC and Credit Suisse First Boston, as from
time to time amended in accordance with its terms.

                                     -16-
<PAGE>

     "ENTITY" shall mean any corporation, firm, unincorporated organization,
association, partnership, a trust (inter vivos or testamentary), an estate of a
deceased, insane or incompetent individual, business trust, joint stock company,
joint venture or other organization, entity or business, whether acting in an
individual, fiduciary or other capacity, or any Authority.

     "EQUITY AGREEMENT" shall mean any one of (i) the ARS Agreement, (ii) the
ATC Stock Purchase Agreement; (iii) the Gearon Agreement, (iv) the ARS Merger
Agreement, and (v) any other agreements approved from time to time by Board of
Directors of ATC pursuant to which Common Stock of ATC may be issued.  "EQUITY
AGREEMENTS" shall mean all of the foregoing agreements.

     "EVENT" shall mean the existence or occurrence of any act, action,
activity, circumstances, condition, event, fact, failure to act, omission,
incident or practice, or any set or combination of any of the foregoing.

     "EXCHANGE ACT" shall mean the Securities Exchange Act of 1934, and the
rules and regulations of the Commission thereunder, all as from time to time in
effect, or any successor law, rules or regulations, and any reference to any
statutory or regulatory provision shall be deemed to be a reference to any
successor statutory or regulatory provision.

     "EXCLUDED OFFERING" shall mean (a) an offering relating solely to dividend
reinvestment plans or stock option or other employee benefit plans, (b) any
merger, consolidation or acquisition, (c) any exchange or tender offer, whether
with existing security holders of ATC or any other Person, or (d) a firm
underwritten offering relating solely to convertible securities or units
consisting of securities senior to Common Stock and warrants, options and rights
to acquire Common Stock in which the managing underwriters shall have objected
to the inclusion of any Registrable Securities.

     "FCC" shall mean the Federal Communications Commission or any successor
Authority.

     "GEARON AGREEMENT" shall mean the Agreement and Plan of Merger, dated as of
November 21, 1997, by and among ATC, American Tower Systems, Inc. (now known as
American Towers, Inc.), Gearon & Co., Inc. and J. Michael Gearon, Jr.

     "GEARON STOCKHOLDERS" shall mean the parties who received ATC Class A
Common Stock in exchange for their capital stock in Gearon & Co., Inc. pursuant
to terms and provisions of the Gearon Agreement.  All registration decisions of
the Gearon Stockholders under this Agreement shall be made by the holders of not
less than a majority in value (based on the proposed public offering) of the
Registrable Securities held by such Gearon Stockholders.

     "LAW"  shall mean any (a) administrative, judicial, legislative or other
action, code, consent decree, constitution, decree, directive, enactment,
finding, law, injunction, interpretation, judgment, order, ordinance, policy
statement, proclamation, promulgation, regulation, requirement, rule, rule of
law, rule of public policy, settlement agreement, statute, or writ of any
Authority, domestic or foreign; (b) the common law, or other legal precedent; or
(c) arbitrator's, mediator's or referee's award, decision, finding or
recommendation.

     "LEGAL ACTION" shall mean, with respect to any Person, any and all
litigation or legal or other actions, arbitrations, counterclaims,
investigations, proceedings, requests for material information by or pursuant to
the order of any Authority or suits, at law or in arbitration, equity or
admiralty, whether or not purported to be brought on behalf of such Person,
affecting such Person or any of such Person's business, property or assets.

                                     -17-
<PAGE>

     "NASD" shall mean the National Association of Securities Dealers, Inc.

     "NASDAQ" shall mean the automatic quotation system of NASD.

     "ORIGINAL REGISTRATION RIGHTS AGREEMENT" is defined in the first Whereas
clause.

     "PERSON" shall mean any natural individual or any Entity.

     "PROSPECTUS" shall mean each prospectus included in any Registration
Statement, as amended or supplemented by any prospectus supplement with respect
to the terms of the offering of any portion of the Registrable Securities
covered by the Registration Statement and by all other amendments and
supplements to the prospectus, including each preliminary prospectus and post-
effective amendments and all material incorporated by reference in such
prospectus.

     "REGISTRABLE SECURITIES" shall mean (a) all shares of Class A Common Stock
acquired by any of the Stockholders (i) pursuant to any of the Equity
Agreements, or (ii) directly or indirectly through one or more such conversions
or exchanges, upon the exercise of conversion or exchange provisions set forth
in other securities of ATC issued pursuant to the provisions of any of the
Equity Agreements, or pursuant to the redemption or repurchase of any such
securities, and (b) all shares of Common Stock of whatever series or class or
other equity securities of ATC derived from the Registrable Securities, whether
as a result of merger, consolidation, stock split, stock dividend, stock
distribution, stock combination, recapitalization or similar event.

     "REGISTRATION EXPENSES" shall mean all (or where appropriate any one or
more) of the following:

          (a)  all registration, filing and listing fees;

          (b)  fees and expenses of compliance with securities or blue sky laws
     (including without limitation reasonable fees and disbursements of counsel
     for the underwriters or selling holders in connection with blue sky and
     state securities qualifications of the Registrable Securities under the
     laws of such jurisdictions as the managing underwriters or the holders of
     not less than a majority in value (based on the proposed public offering
     price) of the Registrable Securities being sold may designate);

          (c)  printing (including without limitation expenses of printing or
     engraving certificates for the Registrable Securities in a form eligible
     for deposit with Depositary Trust Company and otherwise meeting the
     requirements of any securities exchange on which they are listed and of
     printing Prospectuses), word processing, messenger, telephone and delivery
     expenses;

          (d)  fees and disbursements of counsel for ATC, and reasonable fees
     and disbursements of counsel for the underwriters and for the selling
     holders of the Registrable Securities in accordance with the provisions of
     Section 1(c)(xiv) (subject to any provisions to the contrary in this
     Agreement);

          (e)  fees and disbursements of all independent public accountants of
     ATC (including without limitation the expenses of any annual or special
     audit and "cold comfort" letters required by the provisions of this
     Agreement);

          (f)  fees and disbursements of underwriters (excluding discounts,
     commissions or fees of underwriters), selling brokers, dealer managers or
     similar securities industry professionals

                                     -18-
<PAGE>

     relating to the distribution of the Registrable Securities or legal
     expenses of any Person other than ATC, the underwriters and the selling
     holders;

          (g)  securities act liability insurance if ATC so desires or if the
     underwriters or the holders of not less than a majority in value (based on
     the proposed public offering price) of the Registrable Securities being
     sold so require;

          (h)  fees and expenses of other Persons, including any experts,
     retained by ATC;

          (i)  fees and expenses incurred in connection with the listing of the
     Registrable Securities on each securities exchange on which securities of
     the same class are then listed;

          (j)  fees and expenses associated with any NASD filing required to be
     made in connection with any Registration Statement, including, if
     applicable, the fees and expenses of any "qualified independent
     underwriter" (and its counsel) that is required to be retained in
     accordance with the rules and regulations of the NASD;

          (k)  ATC's internal expenses (including without limitation all
     salaries and expenses of its officers and employees performing legal or
     accounting duties); and

          (l)  all other costs and expenses normally associated with the
     issuance and sale of newly issued public securities.

     "REGISTRATION STATEMENT" shall mean any registration statement of ATC which
covers Registrable Securities pursuant to the provisions of this Agreement,
including the Prospectus, amendments, including post-effective amendments to
such registration statement, and supplements to such Prospectus and all exhibits
and all material incorporated by reference in such registration statement.

     "SECURITIES ACT" shall mean the Securities Act of 1933, and the rules and
regulations of the Commission thereunder, all as from time to time in effect, or
any successor law, rules or regulations, and any reference to any statutory or
regulatory provision shall be deemed to be a reference to any successor
statutory or regulatory provision.

     "SIGNIFICANT STOCKHOLDER" shall mean any Stockholder, or group of
Stockholders acting together, which owns not less than the following percentage
or amount of Common Stock:

          (a)  if ATC is not then subject to Section 13 or 15(d) of the Exchange
     Act, (i) shares of Common Stock with a market value (based on the proposed
     public offering price if the Common Stock is not, at the time, publicly
     traded) of not less than $25,000,000, or (ii) 15.38% of the outstanding
     shares of Common Stock (on a fully diluted basis);

          (b)  if ATC is then so subject to Section 13 or 15(d) of the Exchange
     Act, shares of Common Stock with a market value of not less than
     $10,000,000; provided, however, that notwithstanding the foregoing, in the
     event ATC is, at the time of any request made pursuant to the provisions of
     Section 1(b), eligible to file a Registration Statement on Form S-3 (or any
     successor form) with respect to the proposed disposition of the Registrable
     Securities with respect to which such request has been made, and such form
     is acceptable to the holders making such request, the minimum market value
     of the Registrable Securities shall be not less than $5,000,000; and

                                     -19-
<PAGE>

          (c)  J. Michael Gearon, Jr. so long as he holds not less than fifty
     percent (50%) of the shares of Registrable Securities received by him
     pursuant to the consummation of the Gearon Agreement and proposes to
     register shares of Registrable Securities with a market value of not less
     than $10,000,000.

     "STOCKHOLDERS" shall mean those persons who executed this Agreement or who
hereafter become parties to this Agreement by executing a counterpart hereof,
and is further defined in Section 12(a).

     "SUBSIDIARY" shall mean, with respect to any Person, any Entity a majority
of the capital stock ordinarily entitled to vote for the election of directors,
or if no such voting stock is outstanding a majority of the equity interests, of
which is owned directly or indirectly by such Person or any Subsidiary of such
Person.

     12.  Miscellaneous.
          -------------

     (a)  Assignment; Successors and Assigns.  In the event that ATC shall be
merged with, or consolidated into, any other Entity or in the event that it
shall sell and transfer substantially all of its assets to another Entity, the
terms of this Agreement shall inure to the benefit of, and be assumed by, the
Entity resulting from such merger or consolidation, or to which ATC's assets
shall be sold and transferred.  Anything in this Agreement to the contrary
notwithstanding, the term "Stockholders" as used in this Agreement shall be
deemed to include the holders from time to time of any of the Registrable
Securities, whether or not they become parties to this Agreement, except for
holders who have acquired Registrable Securities in connection with an offering
registered under the Securities Act or pursuant to sales made in accordance with
Rule 144 (or any successor rule or regulation or statute in substitution
therefor).  The rights to cause ATC to register Registrable Securities pursuant
to Section 1 may be assigned in connection with any transfer or assignment by a
holder of Registrable Securities; provided, however, that (i) such transfer may
otherwise be effected in accordance with applicable securities laws and (ii)
such transfer is effected in compliance with the restrictions on transfer
contained in any agreement between ATC and such holder.  ATC's obligations under
this Agreement shall not be assigned, and its duties under this Agreement shall
not be delegated, except as provided in the first sentence of this Section.
Nothing in this Agreement expressed or implied is intended to and shall not be
construed to confer upon or create in any Person (other than the parties hereto
and their permitted successors and assigns) any rights or remedies under or by
reason of this Agreement, including without limitation any rights to enforce
this Agreement.

     (b)  Specific Performance; Other Rights and Remedies.  Each party
recognizes and agrees that the other parties' remedies at law for any breach of
the provisions of this Agreement would be inadequate and agrees that for breach
of such provisions, each such party shall, in addition to such other remedies as
may be available to it at law or in equity or as provided in this Agreement, be
entitled to injunctive relief and to enforce its rights by an action for
specific performance to the extent permitted by Law. Each party hereby waives
any requirement for security or the posting of any bond or other surety in
connection with any temporary or permanent award of injunctive, mandatory or
other equitable relief. Nothing herein contained shall be construed as
prohibiting any party from pursuing any other remedies available to it for such
breach or threatened breach, including without limitation the recovery of
damages.

     (c)  Expenses.  Each party shall pay its own expenses incident to the
negotiation, preparation, performance and enforcement of this Agreement
(including all fees and expenses of its counsel, accountants and other
consultants, advisors and representatives for all activities of such persons
undertaken pursuant to this Agreement), except to the extent otherwise
specifically set forth in this Agreement.

                                     -20-
<PAGE>

     (d)  Entire Agreement.  This Agreement constitutes the entire agreement
among the parties with respect to the subject matter hereof and supersedes all
prior agreements, arrangements, covenants, promises, conditions, understandings,
inducements, representations and negotiations, expressed or implied, oral or
written, among them as to such subject matter.

     (e)  Waivers; Amendments.  Notwithstanding anything in this Agreement to
the contrary, amendments to and modifications of this Agreement may be made,
required consents and approvals may be granted, compliance with any term,
covenant, agreement, condition or other provision set forth herein may be
omitted or waived, either generally or in a particular instance and either
retroactively or prospectively with, but only with, the written consent of ATC
(to the extent it is entitled to the benefit thereof) and (i) with respect to
the rights of the Stockholders set forth in Section 1(b), including without
limitation the definition of Significant Stockholder (except with respect to
clause (c) of the definition of Significant Stockholder which cannot be amended
or modified without the prior written consent of J. Michael Gearon, Jr., or his
respective successors or assigns), two-thirds (2/3) in interest of the
Stockholders, and (ii) with respect to all other rights and obligations of the
Stockholders, a majority in interest of the Stockholders (to the extent they are
entitled to the benefit thereof or obligated thereby); provided, however, that
(x) in the event any such amendment, modification, consent, approval or waiver
shall be for the benefit of or materially adverse to less than all of the
Stockholders, such amendment, modification, consent, approval or waiver shall
require a majority in interest of those Stockholders who are not so benefitted
or who are so materially adversely affected and (y) ATC may from time to time
amend this Agreement solely to add Stockholders to this Agreement, subject only
to the approval of the Board of Directors in accordance with Section 6.

     (f)  Notices.  All notices and other communications which by any provision
of this Agreement are required or permitted to be given shall be given in
writing and shall be (a) mailed by first-class or express mail, postage prepaid,
(b) sent by telex, telegram, telecopy or other form of rapid transmission,
confirmed by mailing (by first class or express mail, postage prepaid) written
confirmation at substantially the same time as such rapid transmission, or (c)
personally delivered to the receiving party (which if other than an individual
shall be an officer or other responsible party of the receiving party).  All
such notices and communications shall be mailed, sent or delivered as follows:

     If to American Tower Corporation, at

               116 Huntington Avenue
               Boston, MA 02116
               Attention: Steven B. Dodge, Chairman of the Board and Chief
                          Executive Officer
               Facsimile: (617) 375-7575

          with a copy to:

               Sullivan & Worcester LLP
               One Post Office Square
               Boston, MA  02109
               Attention:  Norman A. Bikales, Esq.
               Facsimile:  (617) 338-2880

     If to any Stockholder, at his address as it appears on the stock records of
     ATC, and/or to such other person(s), telex or facsimile number(s) or
     address(es) as the party to receive any such communication or notice may
     have designated by written notice to the other parties.

                                     -21-
<PAGE>

     (g) Severability.  If any provision of this Agreement shall be held or
deemed to be, or shall in fact be, invalid, inoperative, illegal or
unenforceable as applied to any particular case in any jurisdiction or
jurisdictions, or in all jurisdictions or in all cases, because of the
conflicting of any provision with any constitution or statute or rule of public
policy or for any other reason, such circumstance shall not have the effect of
rendering the provision or provisions in question invalid, inoperative, illegal
or unenforceable in any other jurisdiction or in any other case or circumstance
or of rendering any other provision or provisions herein contained invalid,
inoperative, illegal or unenforceable to the extent that such other provisions
are not themselves actually in conflict with such constitution, statute or rule
of public policy, but this Agreement shall be reformed and construed in any such
jurisdiction or case as if such invalid, inoperative, illegal or unenforceable
provision had never been contained herein and such provision reformed so that it
would be valid, operative and enforceable to the maximum extent permitted in
such jurisdiction or in such case, except when such reformation and construction
could operate as an undue hardship on either party, or constitute a substantial
deviation from the general intent and purpose of such party as reflected in this
Agreement.  The parties shall endeavor in good faith negotiations to replace the
invalid, inoperative, illegal or unenforceable provisions with valid, operative,
legal and enforceable provisions the economic effect of which comes as close as
possible to that of the invalid, inoperative, illegal or unenforceable
provisions.

     (h) Counterparts.  This Agreement may be executed in several counterparts,
each of which shall be deemed an original, but all of which together shall
constitute one and the same instrument, binding upon all the parties hereto.  In
pleading or proving any provision of this Agreement, it shall not be necessary
to produce more than one of such counterparts.

     (i) Section Headings.  The headings contained in this Agreement are for
reference purposes only and shall not in any way affect the meaning or
interpretation of this Agreement.

     (j) Governing Law.  The validity, interpretation, construction and
performance of this Agreement shall be governed by the applicable laws of the
United States of America and the domestic substantive laws of the State of New
York without giving effect to any choice or conflict of laws provision or rule
that would cause the application of domestic substantive laws of any other
jurisdiction.

     (k) Further Acts.  Each party agrees that at any time, and from time to
time, before and after the consummation of the transactions contemplated by this
Agreement, it will do all such things and execute and deliver all such
agreements, assignments, instruments, other documents and assurances, as any
other party or its counsel reasonably deems necessary or desirable in order to
carry out the terms and conditions of this Agreement and the transactions
contemplated hereby or to facilitate the enjoyment of any of the rights created
hereby or to be created hereunder.

                                     -22-
<PAGE>

     IN WITNESS WHEREOF, the parties have executed or caused to be executed
this Agreement as of February 25, 1999.

                      American Tower Corporation

                      By: _____________________________________
                          Name:  Steven B. Dodge
                          Title: Chairman of the Board and Chief Executive
                                 Officer

                      _________________________________________
                      Steven B. Dodge

                      Thomas S. Dodge Irrevocable Trust

                      By:______________________________________
                         Name:
                         Title:

                      Kristen A. Dodge Irrevocable Trust

                      By:______________________________________
                         Name:
                         Title:

                      Benjamin P. Dodge Irrevocable Trust

                      By:______________________________________
                         Name:
                         Title:

                      _________________________________________
                      Norman A. Bikales

                      _________________________________________
                      Alan L. Box

                      _________________________________________
                      Charlton H. Buckley
<PAGE>

                      Chase Equity Associates, L.P.
                      By Chase Capital Partners, General Partner

                      By: _____________________________________
                          Name:  Arnold L. Chavkin
                          Title:  General Partner

                      _________________________________________
                      James S. Eisenstein

                      _________________________________________
                      Arthur C. Kellar

                      _________________________________________
                      Michael B. Milsom

                      _________________________________________
                      Steven J. Moskowitz

                      _________________________________________
                      Joseph L. Winn

                      _________________________________________
                      Thomas H. Stoner

                      Thomas H. Stoner and Bessemer Trust Company,
                      Trustees of Ruth H. Spencer Irrevocable Trust

                      By:______________________________________

                      Bessemer Trust Company, Trustee of
                      Thomas H. Stoner Irrevocable Trust,

                      By:______________________________________

                      _________________________________________
                      Katharine E. Stoner

                      _________________________________________
                      Ruth Rochelle Stoner
<PAGE>

                      _________________________________________
                      Thomas Stoner, Jr.

                      _________________________________________
                      Theodore A. Stoner

                      _________________________________________
                      Katharine E. Stoner, Trustee of
                      Alden Ellsworth Stoner 30 Trust

                      _________________________________________
                      Katharine E. Stoner, Trustee of
                      Lavonne Elizabeth Ellsworth 21 Trust

                      Bessemer Trust Company, Trustee of
                      Alden Elizabeth Stoner 35 Trust

                      By:______________________________________
                         Name:
                         Title:

                      Katharine and Thomas Stoner Foundation

                      By:______________________________________
                         Name:
                         Title:

                      Thomas H. Stoner Charitable Remainder Unitrust
                      dated May 3, 1993

                      By:______________________________________
                         Name:
                         Title:

                      Gearon Stockholders:

                      _________________________________________
                       J. Michael Gearon, Jr.

                      The 1997 Gearon Family Trust

                      _________________________________________
                       By: J.  Michael Gearon, Sr., Trustee

                      _________________________________________
                       Dan King Brainard

                      _________________________________________
                       Jeff Ebihara

                      _________________________________________
                       Doug Wiest
<PAGE>

                      American Tower Corporation Stockholders:

                      _________________________________________
                      Fred R. Lummis

                      Clear Channel Communications, Inc.

                      By:______________________________________
                         Name:
                         Title:

                       Chase Manhattan Capital L.P.

                       By:_____________________________________
                           Name:  Arnold L. Chavkin
                           Title:  General Partner

                      The Spotted Dog Farm, L.P.

                      By:_____________________________________
                         General Partner

                      Webbmont Holdings, L.P.

                      By:_____________________________________
                         General Partner

                      _________________________________________
                      Jack D. Furst

                      Catherine Forgrave Hicks 1993 Trust

                      By:_______________________________________

                      John Alexander Hicks 1984 Trust

                      By:_______________________________________

                      Mack Hardin Hicks 1984 Trust*

                      By:_______________________________________
<PAGE>

                      Robert Bradley Hicks 1984 Trust*

                      By:______________________________________

                      Thomas O. Hicks Jr. 1984 Trust*

                      By:______________________________________

                      _________________________________________

                      Thomas O. Hicks*

                      William Cree Hicks 1992 Trust*

                      By:______________________________________

                      HMTF/Omni Partners, L.P.*

                      By:  Hm3/Omni America Partners, LLC, its General Partner

                      By:_____________________________________
                         Daniel S. Druss
                         Vice President

                      _________________________________________
                      Dan H. Blanks*

                      _________________________________________
                      David R. Deniger*

                      The Melanie Levitt Trust 1996*

                      By:_________________________________________
                         Michael J. Levitt

                      _________________________________________
                      Michael J. Levitt*
<PAGE>

                      The Stephen A. Levitt Trust 1996*

                      By:______________________________________
                         Michael J. Levitt

                      _________________________________________
                      John R. Muse*

                      _________________________________________
                      Lawrence D. Stuart, Jr.*

                      _________________________________________
                      Charles W. Tate*

                      Hicks, Muse, Tate & Furst Incorporated*

                      By:______________________________________

* Hicks, Muse, Tate & Furst Incorporated is hereby appointed as agent for this
signatory for purposes of this agreement.

                      Cox Telecom Towers, Inc.

                      By:______________________________________
                         Name:  Dean Eisner
                         Title: President

                      TeleCom Towers, Inc.

                      By:______________________________________
                         Name: Randall N. Smith
                         Title: Chairman and CEO
<PAGE>

                         USEI Stockholders

                         ______________________________________
                         Name:  James A.R. Veeder

                         ______________________________________
                         Name:  Daniel E. Murphy

                         ______________________________________
                         Name:  Valrie L. Murphy

                         Veeder Family Trust

                         By:______________________________________
                            Name:  James A.R. Veeder
                            Title:  Trustee
<PAGE>

                         Galaxy Engineering Services, Inc. Stockholders:

                         __________________________________________
                         Joseph Forbes

                         Moore Family Holdings, L.P.

                         By:___________________________________________
                            Name:
                            Title:

                         ___________________________________________
                         Paul Blaser

                         ___________________________________________
                         Drew Davis

                         ___________________________________________
                         Louis Roberts

                         __________________________________________
                         John Cody Sutherland

                         ___________________________________________
                         Colin Holland

                         ___________________________________________
                         Jim Bennett

                         Carl R. Moore Family Holdings Limited

                         By:________________________________________
                            Name:  Carl R. Moore
                            Title: Manager
<PAGE>

                      EarleMost Investments, L.P.

                      By:______________________________________
                          Name:  Earle J. Bensing
                          Title: General Partner

                      _________________________________________
                      David Smartt

                      1999 Roy J. Moore II Trust

                      By:______________________________________
                         Carl Moore, as Trustee

                      1999 Brooke Moore Trust

                      By:______________________________________
                         Carl Moore, as Trustee

                      1999 Matthew Moore Trust

                      By:______________________________________
                         Carl Moore, as Trustee

                      _________________________________________
                      Joseph Forbes, as custodian for Julia
                      Marie Forbes pursuant to the U/G/M/A

                      _________________________________________
                      Joseph Forbes, as custodian for Jared
                      Joseph Forbes pursuant to the U/G/M/A
<PAGE>

                      Kline Iron & Steel Co., Inc.

                      By:_______________________________________________
                          Name: Jerome C. Kline
                          Title: President

                      Kline Family Stockholders

                      ___________________________________________________
                      Jerome C. Kline

                      ___________________________________________________
                      Sue David Kline, Trustee for Jerome Carl Kline, Jr.

                      ___________________________________________________
                      Sue David Kline, Trustee for Amy Beth Kline

                      ___________________________________________________
                      Sue David Kline, Trustee for David Bernard Kline
<PAGE>

IN WITNESS WHEREOF, the undersigned hereby executes the Agreement, and hereby
authorizes this signature page to be attached to a counterpart of such Agreement
executed by the other parties thereto.

                      AIRTOUCH COMMUNICATIONS, INC.,
                      a Delaware corporation

                      By: _____________________________________
                          Print Name: Gregory Caligari
                          Title: Assistant Secretary

                      AIRTOUCH CELLULAR,
                      a California corporation

                      By: _____________________________________
                          Print Name: Gregory Caligari
                          Title: Secretary

                      VODAFONE AIRTOUCH LICENSES LLC,
                      a Delaware limited liability company

                      By: Air Touch Communications, Inc.
                      Its Sole Member

                      By: _____________________________________
                          Print Name: Gregory Caligari
                          Title: Assistant Secretary

                      NEW PAR,
                      a Delaware general partnership

                      By: AirTouch Cellular, Inc.
                          A general partner

                      By: _____________________________________
                          Name: Gregory Caligari
                          Title: Secretary
<PAGE>

                      COCONINO, ARIZONA RSA LIMITED PARTNERSHIP, an Arizona
                      limited partnership

                      By: AirTouch Communications, Inc.
                          A general partner

                      By: _____________________________________
                          Print Name: Gregory Caligari
                          Title: Assistant Secretary

                      BOISE CITY MSA LIMTED PARTNERSHIP,
                      a Delaware limited partnership

                      By: AirTouch Communications, Inc.
                          as general partner

                      By: _____________________________________
                          Print Name: Gregory Caligari
                          Title: Assistant Secretary

                      COLORADO RSA NO. 3 LIMITED PARTNERSHIP,
                      a Delaware limited partnership

                      By: AirTouch Communications, Inc.
                          A general partner

                      By: _____________________________________
                          Print Name: Gregory Caligari
                          Title: Assistant Secretary

                      YUMA, ARIZONA RSA LIMITED PARTNERSHIP, an Arizona limited
                      partnership

                      By:  AT Arizona II, LLC
                      Its: General Partner

                      By: Vodafone AirTouch Licenses LLC,
                      Its: Sole Member

                      By: AirTouch Communications, Inc.
                      Its: Sole Member

                      By: _____________________________________
                          Print Name: Gregory Caligari
                          Title: Assistant Secretary
<PAGE>

                      SPOKANE MSA LIMITED PARTNERSHIP,
                      a Delaware limited partnership

                      By: AirTouch Communications, Inc.
                          A general partner

                      By: _____________________________________
                          Print Name: Gregory Caligari
                          Title: Assistant Secretary

                      OLYMPIA CELLULAR LIMITED PARTNERSHIP,
                      a Delaware limited partnership

                      By: AirTouch Communications, Inc.
                          A general partner

                      By: _____________________________________
                          Print Name: Gregory Caligari
                          Title: Assistant Secretary

                      SEATTLE SMSA LIMITED PARTNERSHIP,
                      a Delaware limited partnership

                      By: AirTouch Communications, Inc.
                          as general partner

                      By: _____________________________________
                          Print Name: Gregory Caligari
                          Title: Assistant Secretary

                      SACRAMENTO VALLEY LIMITED PARTNERSHIP,
                      a California limited partnership

                      By: AirTouch Cellular
                          as general partner

                      By: _____________________________________
                          Print Name: Gregory Caligari
                          Title: Assistant Secretary
<PAGE>

                      OMAHA CELLULAR TELEPHONE COMPANY,
                      a New York general partnership

                      By: AirTouch Nebraska, Inc.,
                          A general partner

                      By: _____________________________________
                          Print Name: Gregory Caligari
                          Title: Secretary

                      DES MOINES MSA GENERAL PARTNERSHIP,
                      an Iowa general partnership

                      By: AirTouch Iowa, Inc.
                          A general partner

                      By: _____________________________________
                          Print Name: Gregory Caligari
                          Title: Secretary

                      DULUTH MSA LIMITED PARTNERSHIP,
                      a Delaware limited partnership

                      By: AirTouch Minnesota, Inc.,
                          as general partner

                      By: _____________________________________
                          Print Name: Gregory Caligari
                          Title: Secretary

                      ATHENS CELLULAR, INC.,
                      a Delaware corporation

                      By: _____________________________________
                          Print Name: Gregory Caligari
                          Title: Assistant Secretary
<PAGE>

                      SPRINGFIELD CELLULAR TELEPHONE COMPANY,
                      an Ohio general partnership

                      By: New Par, a General Partnership,
                          as General Partner

                      By: AirTouch Cellular, Inc.
                          A general partner

                      By: _____________________________________
                          Print Name: Gregory Caligari
                          Title: Assistant Secretary

                      HAMILTON CELLULAR TELEPHONE COMPANY,
                      an Ohio general partnership

                      By: New Par, a General Partnership,
                          as General Partner

                      By: AirTouch Cellular, Inc.
                          A general partner

                      By: _____________________________________
                          Print Name: Gregory Caligari
                          Title: Assistant Secretary

                      MUSKEGON CELLULAR PARTNERSHIP,
                      a District of Columbia general partnership

                      By: AirTouch Cellular of Michigan
                          A general partner

                      By: ______________________________________
                          Print Name: Gregory Caligari
                          Title: Assistant Secretary

                      WASATCH UTAH RSA 2 LIMITED PARTNERSHIP,
                      a Delaware limited partnership

                      By: AirTouch Utah, Inc.
                          as general partner

                      By: ______________________________________
                          Print Name: Gregory Caligari
                          Title: Secretary
<PAGE>

                      REDDING MSA LIMITED PARTNERSHIP,
                      a California limited partnership

                      By:  Sacramento Valley Limited Partnership,
                           a Limited Partnership,
                           A general partner

                      By:  AirTouch Cellular
                           as general partner

                      By:______________________________________
                         Print Name: Gregory Caligari
                         Title: Secretary

                      RSA 7 Limited Partnership (IOWA),
                      an Iowa limited partnership

                      By: AirTouch Iowa RSA 7, Inc.
                          A general partner

                      By:______________________________________
                         Print Name: Gregory Caligari
                         Title: Secretary

                      IDAHO RSA NO. 1 LIMITED PARTNERSHIP,
                      a Delaware limited partnership

                      By:  AirTouch Communications, Inc.,
                           A general partner

                      By:______________________________________
                         Print Name: Gregory Caligari
                         Title: Secretary

                      IDAHO RSA NO. 2 LIMITED PARTNERSHIP,
                      a Delaware limited partnership

                      By:  AirTouch Idaho, Inc.,
                           as general partner

                      By:______________________________________
                         Print Name: Gregory Caligari
                         Title: Secretary
<PAGE>

                      IDAHO RSA 3 LIMITED PARTNERSHIP,
                      a Delaware limited partnership

                      By:  AirTouch Idaho, Inc.,
                           as general partner

                      By:______________________________________
                         Print Name: Gregory Caligari
                         Title: Secretary

                      MODOC RSA LIMITED PARTNERSHIP,
                      a California limited partnership

                      By:  AirTouch Cellular
                           as general partner

                      By:______________________________________
                         Print Name: Gregory Caligari
                         Title: Secretary

                      GREAT SALT FLATS GENERAL PARTNERSHIP,
                      an Utah general partnership

                      By: AirTouch Utah, Inc.
                          A general partner

                      By:______________________________________
                         Print Name: Gregory Caligari
                         Title: Secretary
<PAGE>

IN WITNESS WHEREOF, the undersigned hereby executes the Amended and Restated
Registration Rights Agreement, and hereby authorizes this signature page to be
attached to a counterpart of such Agreement executed by the other parties
thereto.

                      Publicom Stockholders

                      _____________________________________
                      Name: Ana M. Diaz

                      Sheridan Dickinson Revocable Trust

                      By:__________________________________
                         Name:  Sheridan Dickinson, Sr.
                         Title:  Trustee

                      _____________________________________
                      Name:  Sheridan Dickinson, Jr.

                      _____________________________________
                      Name:  Julian Gonzalez

                      _____________________________________
                      Name:  Jaime Dickinson

American Tower Corporation hereby
acknowledges and consents to the Publicom
Stockholders identified above becoming
parties as Stockholders to the Amended and
Restated Registration Rights Agreement

AMERICAN TOWER CORPORATION

By:_________________________
   Name: Michael B. Milsom
   Title: Vice President
<PAGE>

IN WITNESS WHEREOF, the undersigned hereby executes the Amended and Restated
Registration Rights Agreement, and hereby authorizes this signature page to be
attached to a counterpart of such Agreement executed by the other parties
thereto.

                                  Tower Ventures, Inc. stockholders

                                  ____________________________________
                                  William P. Collatos

                                  ____________________________________
                                  Joseph V. Gallagher

                                  ____________________________________
                                  Robert J. Maccini

                                  ____________________________________
                                  C. Kevin Landry

                                  The Applegate Family Trust

                                  ____________________________________
                                  By: Brion B. Applegate
                                  Title: Trustee

                                  ____________________________________
                                  Linda C. Wisnewski

                                  ____________________________________
                                  Kristen S. Maccini
<PAGE>

American Tower Corporation hereby acknowledges and consents to the Tower
Ventures stockholders identified above becoming parties as Stockholders to the
Amended and Restated Registration Rights Agreement

AMERICAN TOWER CORPORATION

By:
    ______________________
    Name:  Ross W. Elder
    Title: Vice President
<PAGE>

IN WITNESS WHEREOF, the undersigned hereby executes the Agreement, and hereby
authorizes this signature page to be attached to a counterpart of such Agreement
executed by the other parties thereto.

                              Flash Stockholder

                              ____________________________________
                              Name: William F. Somers

American Tower Corporation hereby
acknowledges and consents to the Flash
Stockholder identified above becoming
a party as Stockholder to the Amended and
Restated Registration Rights Agreement

AMERICAN TOWER CORPORATION

By:
    _____________________________
    Name:  Justin D. Benincasa
    Title:  Senior Vice President
<PAGE>

IN WITNESS WHEREOF, the undersigned hereby executes the Agreement, and hereby
authorizes this signature page to be attached to a counterpart of such Agreement
executed by the other parties thereto.

                              Modern Stockholder

                              _____________________________
                              Name: William F. Somers

American Tower Corporation hereby
acknowledges and consents to the Modern
Stockholder identified above becoming
a party as Stockholder to the Amended and
Restated Registration Rights Agreement

AMERICAN TOWER CORPORATION

By:
    _____________________________
    Name:  Justin D. Benincasa
    Title:  Senior Vice President
<PAGE>

IN WITNESS WHEREOF, the undersigned hereby executes the Amended and Restated
Registration Rights Agreement, and hereby authorizes this signature page to be
attached to a counterpart of such Agreement executed by the other parties
thereto.

                                  Vancomm, Inc. stockholders

                                  ____________________________________
                                  Jerry Glaser

                                  ____________________________________
                                  Michael Moskowitz

                                  ____________________________________
                                  Paul Papay

                                  ____________________________________
                                  Peter Papay
<PAGE>

American Tower Corporation hereby
acknowledges and consents to the Vancomm,
Inc. stockholders identified above becoming
a party as Stockholders to the Amended and
Restated Registration Rights Agreement

AMERICAN TOWER CORPORATION

By:_____________________________
   Name:  Justin D. Benincasa
   Title:  Senior Vice President
<PAGE>

IN WITNESS WHEREOF, the undersigned hereby execute the Amended and Restated
Registration Rights Agreement, and hereby authorizes this signature page to be
attached to a counterpart of such Agreement  executed by the other parties
thereto.

                    ________________________________________________
                    Access Technology Partners, L.P.

                    ________________________________________________
                    Access Technology Partners Brokers Fund, L.P.

                    ________________________________________________
                    Joseph T. Arsenio II

                    ________________________________________________
                    Jeffrey Barbakow

                    ________________________________________________
                    BayStar Capital, L.P.

                    ________________________________________________
                    Bay Star International Ltd.

                    ________________________________________________
                    David & Annika Bernstein

                    ________________________________________________
                    Stanley & Charlotte Bernstein

                    ________________________________________________
                    Stephen & Gayle Bernstein

                    ________________________________________________
                    CBK Investments, G.P.

                    ________________________________________________
                    Hector Chao

                    ________________________________________________
                    Liz Chow

                    ________________________________________________
                    City National Bank, Trustee

                    ________________________________________________
                    David Vaun Crumly

                    ________________________________________________
                    Crumly Family Partners Limited

                    ________________________________________________
                    Richard d'Abo

                    ________________________________________________
                    Delaware Charter Guarantee & Trust Co.,
                    Cust. Joseph T. Arsenio II

                    ________________________________________________
                    Delaware Charter Guarantee & Trust Co.,
                    Cust. Joseph T. Arsenio II, IRA

                    ________________________________________________
                    Delaware Charter Guarantee & Trust Co.,
                    Cust. Joseph T. Arsenio II, IRA Rollover

                    ________________________________________________
                    Delaware Charter Guarantee & Trust Co.,
                    Cust. Joseph T. Arsenio II, IRA SEP

                    ________________________________________________
                    Andrew & Donna Dietz

                    ________________________________________________
                    Irene B. Dorsey

                    ________________________________________________
                    Evergreen Trust, U/A/D 6-12-90

                    ________________________________________________
                    Bruce and Patricia Fisher

                    ________________________________________________
                    Jonathan Gans

                    ________________________________________________
                    Rock Steven Gnatovich

                    ________________________________________________
                    David Golden

                    ________________________________________________
                    Howard Goldman

                    ________________________________________________
                    Gotel Investments Ltd.

                    ________________________________________________
                    Bruce J. Greenbaum & Teri Greenbaum,
                    Trustees

                    ________________________________________________
                    Ruth Greenbaum & Monroe A. Greenbaum, Trustees

                    ________________________________________________
                    Scott D. & Susan B. Greenbaum

                    ________________________________________________
                    Eliezer A. Gurfel III

                    ________________________________________________
                    Barry L. Guterman and Sheryl L. Guterman,
                    Co-Trustees

                    ________________________________________________
                    Ken Halloway

                    ________________________________________________
                    Hambrecht & Quist California

                    ________________________________________________
                    Hambrecht & Quist Employee Venture
                    Fund L.P. II

                    ________________________________________________
                    Terry Hanson

                    ________________________________________________
                    Peter Hartz, Trustee U/A dtd 9/20/90 by
                    Hartz Revocable Trust

                    ________________________________________________
                    Carl Hirsch

                    ________________________________________________
                    Intel Corporation

                    ________________________________________________
                    Charles Isgar

                    ________________________________________________
                    Yolanta Jakubiec

                    ________________________________________________
                    June Investments, LLC

                    ________________________________________________
                    Kinda Associates, a Massachusetts General
                    Partnership

                    ________________________________________________
                    James Koisrud

                    ________________________________________________
                    James Koisrud & Sookhi Ro

                    ________________________________________________
                    Donald J. Kula

                    ________________________________________________
                    Mike Labriola

                    ________________________________________________
                    Evelyn Lee

                    ________________________________________________
                    Sandra J. Levin

                    ________________________________________________
                    James and Linda Lippman 1989 Trust:
                    James Lippman

                    ________________________________________________
                    Max Loubiere

                    ________________________________________________
                    Jon Mansey

                    ________________________________________________
                    Steve Meepos

                    ________________________________________________
                    Brett Messing

                    ________________________________________________
                    Brian Messing

                    ________________________________________________
                    Brian and Sandy Messing

                    ________________________________________________
                    Debra Messing

                    ________________________________________________
                    Natalie Messing, UGMA, Brett Messing,
                    Custodian

                    ________________________________________________
                    Samantha Messing, UGMA, Brett Messing,
                    Custodian

                    ________________________________________________
                    Steven J. Miller

                    ________________________________________________
                    Carlos Moran

                    ________________________________________________
                    Chris Mulhern

                    ________________________________________________
                    Mia Mulhern

                    ________________________________________________
                    Tom Mulhern

                    ________________________________________________
                    Michael Nesmith

                    ________________________________________________
                    Newberg Family Trust dated 12-18-90

                    ________________________________________________
                    Barry Newburger

                    ________________________________________________
                    Mira Nikolic

                    ________________________________________________
                    Norman Pattiz, Trustee, Pattiz Family Trust

                    ________________________________________________
                    Philip Michael Nunez & Debora Weston Nunez

                    ________________________________________________
                    Alyssa Pearlstein, UGMA, David Pearlstein,
                    Custodian

                    ________________________________________________
                    David and Gina Pearlstein

                    ________________________________________________
                    Nicole Pearlstein, UGMA, David
                    Pearlstein, Custodian

                    ________________________________________________
                    Sonny Pearlstein

                    ________________________________________________
                    Sonny and Marsha Pearlstein

                    ________________________________________________
                    Zachary Pearlstein, UGMA, David Pearlstein,
                    Custodian

                    ________________________________________________
                    Jim Petit

                    ________________________________________________
                    Pequot Private Equity Fund II, L.P.

                    ________________________________________________
                    R&M Interpacket Investors, G.P.

                    ________________________________________________
                    Bruce Raben

                    ________________________________________________
                    Josh Rafner

                    ________________________________________________
                    Mitchell S. Rosenzweig

                    ________________________________________________
                    Alan Rothenberg

                    ________________________________________________
                    Mark Rubin

                    ________________________________________________
                    Allen Sciarillo

                    ________________________________________________
                    Robert Schiowitz

                    ________________________________________________
                    The Sear Family Trust

                    ________________________________________________
                    Lori Segaux

                    ________________________________________________
                    Michael J. Shepard

                    ________________________________________________
                    Steven & Janine Simenhoff

                    ________________________________________________
                    Julie Spira, as Trustee, The Julia Spira Inter
                    Vivos Trust dated June 22, 2000

                    ________________________________________________
                    Jeffrey Sudikoff

                    ________________________________________________
                    Timothy F. Sylvester

                    ________________________________________________
                    George & Lenore Travis

                    ________________________________________________
                    Bruce Tyson, Trustee for Evergreen Trust,
                    U/A/D 6-12-90

                    ________________________________________________
                    Juliana Long Tyson, UGMA Bruce Tyson,
                    Custodian

                    ________________________________________________
                    VF Family Partnership

                    ________________________________________________
                    Paul Vogel

                    ________________________________________________
                    Gary Vollen

                    ________________________________________________
                    W2 Ventures Partners, LLC

                    ________________________________________________
                    Alan E. & Stephanie C. Weston, Trustees

                    ________________________________________________
                    Craig E. Weston

                    ________________________________________________
                    Rodney & Judith Williams

                    ________________________________________________
                    William Wisniewski

                    ________________________________________________
                    Bob Wotherspoon

                    ________________________________________________
                    John Yona

                    ________________________________________________
                    Loveday Ziluca

                    ________________________________________________
                    Kenneth H. Zimble

                    ________________________________________________
                    Lisa Zimble

                    ________________________________________________
                    Oliver Zimble, UGMA, Peter Zimble,
                    Custodian

                    ________________________________________________
                    Patricia E. Cohen Zimble Trust

                    ________________________________________________
                    Peter Zimble

                    ________________________________________________
                    Shari Zimble

American Tower Corporation hereby
acknowledges and consents to the above
named holders of InterPacket Stock
becoming a party as a Stockholder to the
Amended and Restated Registration Rights
Agreement

AMERICAN TOWER CORPORATION

By:______________________________
   Authorized Officer:

<PAGE>

IN WITNESS WHEREOF, the undersigned hereby execute the Agreement, and hereby
authorize this signature page to be attached to a counterpart of such Agreement
executed by the other parties thereto.

                    By:________________________
                       Name: Joseph J. Catapano

                    By:________________________
                       Name: Joseph P. Catapano

American Tower Corporation hereby
acknowledges and consents to each
individual listed above becoming a
party as Stockholder to the Amended
and Restated Registration Rights
Agreement

AMERICAN TOWER CORPORATION

By:____________________________
   Name: Justin D. Benincasa
   Title: Senior Vice PresidentAMENDMENT #7 TO CONSULTING AGREEMENT

Exhibit 10.1 

 AMENDMENT #7 TO 

CONSULTING AGREEMENT 

         This Amendment #7 to Consulting Agreement, dated as of May 16, 2001, hereby amends the terms of that certain Consulting Agreement dated November 17, 1995, as amended, (hereinafter "Consulting
Agreement") by and between Parametric Technology Corporation, a Massachusetts corporation, having its principal business address at 140 Kendrick Street, Needham, Massachusetts 02494 (hereinafter "PTC") and Michael E. Porter, an individual currently
residing at 44 Green Hill Road, Brookline, Massachusetts 02146 (hereinafter "Consultant").

ARTICLE 3 SERVICES TO BE PERFORMED BY CONSULTANT, is hereby amended by adding the following Section 3.7: 
 3.7 Consultant is engaged pursuant to this Amendment #6 to Consulting Agreement, to participate in the following: 

(a) one (1) top management seminar (i.e. Chief Information Officer (CIO) seminar) consistent with the purposes and scope which Consultant was previously engaged to provide under Article 3 of the Consulting Agreement. 

 (b) a Customer Advisory Board to help identify and develop business strategies and opportunities in the European market and raise PTC's visibility with senior executives in Europe. 

 ARTICLE 4 COMPENSATION AND EXPENSES, is hereby amended by adding the following Section 4.8:

 4.8 OPTION GRANT FOR SERVICES TO BE PERFORMED UNDER SECTION 3.7. In connection with those services to be performed pursuant to Amendment #7 to Consulting Agreement (as described in Section 3.7 above), Consultant shall receive an option to
purchase 20,000 shares of PTC's common stock, $.01 par value per share, under the terms of the Stock Option Agreement dated May 16, 2001 between PTC and the Consultant attached hereto. 

        IN WITNESS WHEREOF, the parties have executed this Amendment #7 to Consulting Agreement as of the date and year first above written.

 

	 	 	 
	CONSULTANT	 	PARAMETRIC TECHNOLOGY CORPORATION 
	 	 	 
	/s/ Michael Porter

 	 	/s/ C. Richard Harrison

 
	Michael E. Porter	 	C. Richard Harrison

President and Chief Executive Officer 
	 	 	 

 

	 	 	 
	No. 042791	 	 20,000 Shares 

	 	 	 

 

 PARAMETRIC TECHNOLOGY CORPORATION

 2000 EQUITY INCENTIVE PLAN 

 Nonstatutory Stock Option Certificate 

         Parametric Technology Corporation (the "Company"), a Massachusetts corporation, hereby grants to the person named below an option to purchase shares of Common Stock, $0.01 par value, of the Company
(the "Option") under and subject to the Company's 2000 Equity Incentive Plan (the "Plan") exercisable on the terms and conditions set forth below and those attached hereto and in the Plan: 

 

	 	 	 
	Name of Optionholder: 	 	Michael E. Porter 
	 	 	 
	Social Security Number	 	  
	 	 	 
	Number of Shares: 	 	20,000 
	 	 	 
	Option Price:	 	 $13.00
	 	 	 
	Date of Grant: 	 	May 16, 2001 
	 	 	 
	Expiration: 	 	May 16, 2006 
	 	 	 
	Exercisability Schedule: 	 	 
	 	 	 
	on or after May 16, 2001, as to 50% of the shares,
	on or after July 16, 2001, as to 50% of the shares.
	 	 	 

provided that Optionholder's consulting agreement with the Company is not terminated earlier, in which event the Option, (i) to the extent exercisable at the date of such termination, may not be exercised as to any shares after the expiration of
seven (7) months from the date of such termination, and (ii) to the extent not exercisable at the date of such termination, shall be canceled as to any such shares effective on the date of such termination. 

        This option shall not be treated as an Incentive Stock Option under section 422 of the Internal Revenue Code of 1986, as amended (the "Code").
         By acceptance of this Option, the Optionholder agrees to the terms and conditions set forth above and those attached hereto and in the Plan.

	 	 	 
	OPTIONHOLDER	 	PARAMETRIC TECHNOLOGY CORPORATION 
	 	 	 
	By: /s/ Michael E. Porter

 	 	By: /s/ C. Richard Harrison

 
	Michael E. Porter	 	C. Richard Harrison

President and Chief Executive Officer 
	 	 	 

 

 PARAMETRIC TECHNOLOGY CORPORATION 2000 EQUITY INCENTIVE PLAN

 NONSTATUTORY STOCK OPTION TERMS AND CONDITIONS 

 1. Plan Incorporated by Reference. This Option is issued pursuant to the terms of the Plan and may be amended as provided in the Plan. Capitalized terms used and not otherwise defined in this certificate have the meanings given to them in
the Plan. This certificate does not set forth all of the terms and conditions of the Plan, which are incorporated herein by reference. The Committee administers the Plan and its determinations regarding the operation of the Plan are final and
binding. Copies of the Plan may be obtained upon written request without charge from the Legal Department of the Company. 

 2. Option Price. The price to be paid for each share of Common Stock issued upon exercise of the whole or any part of this Option is the Option Price set forth on the face of this certificate.

 3. Exercisability Schedule. This Option may be exercised at any time and from time to time for the number of shares and in accordance with the exercisability schedule set forth on the face of this certificate, but only for the purchase of
whole shares. This Option may not be exercised as to any shares after the Expiration date. This Option may be terminated by the Company before the Expiration Date as permitted by the Plan.

 4. Method of Exercise. To exercise this Option, the Optionholder shall deliver written notice of exercise to the Company specifying the number of shares with respect to which the Option is being exercised accompanied by payment of the
Option Price for such shares in cash, by certified check or in such other form, including, to the extent then permitted by the Committee, shares of Common Stock of the Company valued at their Fair Market Value on the date of delivery or a payment
commitment of a financial or brokerage institution, as the Committee may approve. Promptly following such notice, the Company will deliver to the Optionholder a certificate representing the number of shares with respect to which the Option is being
exercised. 

5. No Right To Employment. No person shall have any claim or right to be granted an Option. Each employee of the Company or any of its Affiliates is an employee-at-will (that is to say that either the Participant or the Company or any
Affiliate may terminate the employment relationship at any time for any reason or no reason at all) unless, and only to the extent, provided in a written employment agreement for a specified term executed by the chief executive officer of the
Company or his duly authorized designee or the authorized signatory of any Affiliate. Neither the adoption, maintenance, nor operation of the Plan nor any Option hereunder shall confer upon any employee of the Company or of any Affiliate any right
with respect to the continuance of his/her employment by the Company or any such Affiliate nor shall they interfere with the right of the Company (or Affiliate) to terminate any employee at any time or otherwise change the terms of employment,
including, without limitation, the right to promote, demote or otherwise re-assign any employee from one position to another within the Company or any Affiliate.
 6. Effect of Grant. Optionholder shall not earn any Options granted hereunder until such time as all the conditions set forth herein and in the Plan which are required to be met in order to exercise the Option have been fully satisfied.

 7. Change of Control. In order to preserve the Optionholder's rights under the Option in the event of a change in control of the Company (as defined by the Committee), the Committee in its discretion may at any time take one or more of
the following actions: (i) provide for the acceleration of any time period relating to the exercise of the Option, (ii) provide for payment to the Optionholder of cash or other property with a Fair Market Value equal to the amount that would have
been received upon the exercise or payment of the Option had the Option been exercised or paid upon the change in control, (iii) adjust the terms of the Option in a manner determined by the Committee to reflect the change in control, (iv) cause the
Option to be assumed, or new rights substituted therefor, by another entity, or (v) make such other provision as the Committee may consider equitable to Optionholder and in the best interests of the Company.

 8. Option Not Transferable. This Option is not transferable by the Optionholder other than by will or the laws of descent and distribution, and is exercisable, during the Optionholder's lifetime, only by the Optionholder. The naming of a
Designated Beneficiary does not constitute a transfer.

 9. Termination of Employment or Engagement. If the Optionholder's status as an employee or consultant of (a) the Company, (b) an Affiliate, or (c) a corporation (or parent or subsidiary corporation of such corporation) issuing or assuming
a stock option in a transaction to which section 424(a) of the Code applies, is terminated for any reason (voluntary or involuntary), (i) this Option

shall not thereafter become exercisable as to any additional shares and (ii) if the period of exercisability for this Option following such termination has not been specified by the Board, the vested portion of this Option shall remain
exercisable (to the extent not previously exercised) for ten (10) calendar days after the day on which the Participant's employment or engagement is terminated, whereupon this Option shall terminate; except that 

        (a) If the Participant is on military, sick leave or other leave of absence approved by the Company, his or her employment or engagement with the Company will be treated as continuing intact if the
period of such leave does not exceed ninety (90) days, or, if longer, so long as the Participant's right to reemployment or the survival of his or her service arrangement with the Company is guaranteed either by statute or by contract; otherwise,
the Participant's employment or engagement will be deemed to have terminated on the 91st day of such leave.
         (b) If the Participant's employment is terminated by reason of his or her retirement from the Company at normal retirement age, each Option then held by the Participant, to the extent exercisable
at retirement, may be exercised by the Participant at any time within three (3) months after such retirement unless terminated earlier by its terms. 

        (c) If the Participant's employment or engagement is terminated by reason of his or her death, each Option then held by the Participant, to the extent exercisable at the date of death, may be exercised
at any time within one year after that date (unless terminated earlier by its terms) by the person(s) to whom the Participant's option rights pass by will or by the applicable laws of descent and distribution.

         (d) If the Participant's employment or engagement is terminated by reason of his or her becoming permanently and totally disabled, each Option then held by the Participant, to the extent
exercisable upon the occurrence of permanent and total disability, may be exercised by the Participant at any time within one (1) year after such occurrence unless terminated earlier by its terms. For purposes hereof, an individual shall be deemed
to be "permanently and totally disabled" if he or she is unable to engage in any substantial gainful activity by reason of any medically determinable physical or mental impairment which can be expected to result in death or which has lasted or can
be expected to last for a continuous period of not less than twelve (12) months. Any determination of permanent and total disability shall be made in good faith by the Company on the basis of a report signed by a qualified physician. 

10. Compliance with Securities Laws. It shall be a condition to the Optionholder's right to purchase shares of Common Stock hereunder that the Company may, in its discretion, require (a) that the shares of Common Stock reserved for issuance
upon the exercise of this Option shall have been duly listed, upon official notice of issuance, upon any national securities exchange or automated quotation system on which the Company's Common Stock may then be listed or quoted, (b) that either (i)
a registration statement under the Securities Act of 1933 with respect to the shares shall be in effect, or (ii) in the opinion of counsel for the Company, the proposed purchase shall be exempt from registration under that Act and the Optionholder
shall have made such undertakings and agreements with the Company as the Company may reasonably require, and (c) that such other steps, if any, as counsel for the Company shall consider necessary to comply with any law applicable to the issue of
such shares by the Company shall have been taken by the Company or the Optionholder, or both. The certificates representing the shares purchased under this Option may contain such legends as counsel for the Company shall consider necessary to comply
with any applicable law.
 11. Payment of Taxes. The Optionholder shall pay to the Company, or make provision satisfactory to the Committee for payment of, any taxes required by law to be withheld with respect to the exercise of the Option no later than the date of
the event creating the tax liability. The Company and its Affiliates may, to the extent permitted by law, deduct any such tax obligations from any payment of any kind due to the Optionholder. In the Committee's discretion, the minimum tax
obligations required by law to be withheld with respect to the exercise of the Option may be paid in whole or in part in shares of Common Stock, including shares retained from the exercise of the Option, valued at their Fair Market Value on the date
of retention. 

Adopted: February 10, 2000

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