UNITED STATES
                      SECURITIES AND EXCHANGE COMMISSION
                            WASHINGTON, D.C. 20549

                                   FORM 11-K
                                 ANNUAL REPORT

                       PURSUANT TO SECTION 15(D) OF THE
                        SECURITIES EXCHANGE ACT OF 1934

(Mark One:)
[X] ANNUAL REPORT PURSUANT TO SECTION 15(d) OF THE SECURITIES EXCHANGE ACT OF
1934 [NO FEE REQUIRED, EFFECTIVE OCTOBER 7, 1996].

For the fiscal year ended December 31, 2000

                                      OR

[ ] TRANSITION REPORT PURSUANT TO SECTION 15(d) OF THE SECURITIES EXCHANGE ACT
OF 1934 [NO FEE REQUIRED].

For the transition period from___________to ____________

                           Commission file number 001-14195
                           --------------------------------

  A. Full title of the plan and the address of the plan, if different from
that of the issuer named below:

                    AMERICAN TOWER RETIREMENT SAVINGS PLAN

  B. Name of issuer of the securities held pursuant to the plan and the address
of its principal executive office:

                          AMERICAN TOWER CORPORATION
                             116 Huntington Avenue
                          Boston, Massachusetts 02116


                                AMERICAN TOWER
                            RETIREMENT SAVINGS PLAN


                               TABLE OF CONTENTS
------------------------------------------------------------------------------------------------------
                                                                                                  Page

                                                                                               
INDEPENDENT AUDITORS' REPORT                                                                        3

FINANCIAL STATEMENTS AS OF AND FOR THE YEARS ENDED DECEMBER 31, 2000 AND 1999:

 Statements of Net Assets Available for Benefits                                                    4

 Statements of Changes in Net Assets Available for Benefits                                         5

 Notes to Financial Statements                                                                    6-9

SUPPLEMENTAL SCHEDULES AS OF AND FOR THE YEAR ENDED DECEMBER 31, 2000:

 Schedule H, Part IV, Line 4a - Schedule of Nonexempt Transactions                                 10

 Schedule H, Part IV, Line 4i - Schedule of Assets Held for Investment Purposes at End of Year     11


Schedules required under the Employee Retirement Income Security Act of 1974,
other than the schedules listed above, are omitted because of the absence of
conditions under which such schedules are required.

                                       2


INDEPENDENT AUDITORS' REPORT

To the Plan Administrator of
 American Tower Retirement Savings Plan
116 Huntington Avenue
Boston, MA  02116

We have audited the accompanying statements of net assets available for benefits
of the American Tower Retirement Savings Plan (the "Plan") as of December 31,
2000 and 1999, and the related statements of changes in net assets available for
benefits for the years then ended.  These financial statements are the
responsibility of the Plan's management.  Our responsibility is to express an
opinion on these financial statements based on our audits.

We conducted our audits in accordance with auditing standards generally accepted
in the United States of America.  Those standards require that we plan and
perform the audit to obtain reasonable assurance about whether the financial
statements are free of material misstatement.  An audit includes examining, on a
test basis, evidence supporting the amounts and disclosures in the financial
statements.  An audit also includes assessing the accounting principles used and
significant estimates made by management, as well as evaluating the overall
financial statement presentation.  We believe that our audits provide a
reasonable basis for our opinion.

In our opinion, such financial statements present fairly, in all material
respects, the net assets available for benefits of the Plan as of December 31,
2000 and 1999, and the changes in net assets available for benefits for the
years then ended, in conformity with accounting principles generally accepted in
the United States of America.

Our audits were conducted for the purpose of forming an opinion on the basic
financial statements taken as a whole.  The supplemental schedules listed in the
Table of Contents are presented for the purpose of additional analysis and are
not a required part of the basic financial statements, but are supplementary
information required by the Department of Labor's Rules and Regulations for
Reporting and Disclosure under the Employee Retirement Income Security Act of
1974.  These schedules are the responsibility of the Plan's management.  Such
schedules have been subjected to the auditing procedures applied in our audit of
the basic 2000 financial statements and, in our opinion, are fairly stated in
all material respects when considered in relation to the basic financial
statements taken as a whole.


/s/ Deloitte & Touche LLP
Boston, MA
June 22, 2001

                                       3


AMERICAN TOWER
RETIREMENT SAVINGS PLAN

STATEMENTS OF NET ASSETS AVAILABLE FOR BENEFITS
DECEMBER 31, 2000 AND 1999
--------------------------------------------------------------------------------

                                                        2000        1999
                                                        ----        ----

ASSETS:
 Investments, at fair value:
  Mutual funds                                       $19,042,137  $8,982,545
  Common stock                                           427,784          --
  Participant loans                                      375,131      56,862
                                                     -----------  ----------

     Total investments                                19,845,052   9,039,407

 Contributions receivable                                725,052     461,892
                                                     -----------  ----------

NET ASSETS AVAILABLE FOR BENEFITS                    $20,570,104  $9,501,299
                                                     ===========  ==========

                       See notes to financial statements

                                       4


AMERICAN TOWER
RETIREMENT SAVINGS PLAN

STATEMENTS OF CHANGES IN NET ASSETS AVAILABLE FOR BENEFITS
YEARS ENDED DECEMBER 31, 2000 AND 1999
--------------------------------------------------------------------------------



                                                                                     2000              1999
                                                                                 -----------        ----------
                                                                                              
ADDITIONS:
  Investment activity:
    Net (depreciation) appreciation in fair value of investments                 $(2,024,684)       $1,184,010
    Dividends and interest                                                         1,207,588           498,163
                                                                                 -----------        ----------

           Net investment activity                                                  (817,096)        1,682,173
                                                                                 -----------        ----------

  Contributions:
    Participant                                                                   10,361,677         3,538,144
    Employer                                                                       1,525,372           500,622
                                                                                 -----------        ----------

           Total contributions                                                    11,887,049         4,038,766
                                                                                 -----------        ----------

           Total additions                                                        11,069,953         5,720,939
                                                                                 -----------        ----------

DEDUCTIONS:
  Benefits paid to participants                                                     (789,938)         (327,175)
  Administrative expenses                                                            (47,837)          (29,767)
                                                                                 -----------        ----------

           Total deductions                                                         (837,775)         (356,942)
                                                                                 -----------        ----------

NET INCREASE BEFORE TRANSFERS                                                     10,232,178         5,363,997

TRANSFERS IN FROM OTHER PLANS                                                        836,627         2,110,720
                                                                                 -----------        ----------

NET INCREASE                                                                      11,068,805         7,474,717

NET ASSETS AVAILABLE FOR BENEFITS:
  Beginning of year                                                                9,501,299         2,026,582
                                                                                 -----------        ----------

  End of year                                                                    $20,570,104        $9,501,299
                                                                                 ===========        ==========


                      See notes to financial statements.


                                       5


AMERICAN TOWER
RETIREMENT SAVINGS PLAN

NOTES TO FINANCIAL STATEMENTS

1. DESCRIPTION OF THE PLAN

   The following description of the American Tower Retirement Savings Plan (the
   "Plan") provides only general information.  Participants should refer to the
   Plan agreement for a more complete description of the Plan's provisions.

   GENERAL INFORMATION - The Plan, effective July 14, 1998, is a defined
   contribution plan available to substantially all full-time employees of
   American Tower Corporation and subsidiaries (the "Company").  The Company, as
   Plan administrator, controls and manages the operation and administration of
   the Plan.  Fidelity Management Trust Company serves as the trustee of the
   Plan.  The Plan is subject to the provisions of the Employee Retirement
   Income Security Act of 1974 ("ERISA").

   PARTICIPANT CONTRIBUTIONS - Each year, participants may contribute up to 15%
   of pretax annual compensation, as defined in the Plan, subject to limits set
   by the Internal Revenue Code (the "Code").  Participants may also contribute
   amounts representing distributions from other qualified plans.

   EMPLOYER CONTRIBUTIONS - Each year, the Company may make discretionary
   matching contributions to be determined annually based on a percentage of an
   employee's pretax contributions.  Matching contributions are subject to a
   maximum of 5% of an employee's eligible compensation contributed to the Plan.
   For 2000 and 1999, the matching contribution was 35% and 30%, respectively,
   of the first 5% contributed by a participant.

   PARTICIPANT ACCOUNTS - Each participant's account is credited with the
   participant's contributions and withdrawals, as applicable, and allocations
   of (a) the Company's contributions and (b) Plan earnings.    Allocations are
   based on participant earnings or account balances, as defined.  The benefit
   to which a participant is entitled is the benefit that can be provided from
   his or her account.

   VESTING - Participants are immediately vested in their contributions plus
   actual earnings thereon.  Vesting in the Company contribution portion of
   their accounts (plus actual earnings thereon) is based on years of credited
   service.  A participant will vest 20% each year until fully vested.

   PAYMENT OF BENEFITS - Total or partial cash distributions from the Plan are
   permitted upon a participant's attainment of age 59 1/2, termination of
   employment, retirement, death or disability.  In addition, withdrawals are
   also permitted for certain events that result in financial hardship to the
   participant.  A participant may make only one withdrawal in any consecutive
   12-month period.

   FORFEITURES - Unvested employer contributions and earnings thereon that have
   been forfeited are initially applied against administrative expenses of the
   Plan.  Any excess forfeitures are applied to reduce future employer
   contributions.

                                       6


1. DESCRIPTION OF THE PLAN (CONTINUED)

   PARTICIPANT LOANS - Participants may borrow from their accounts a minimum of
   $1,000.  The maximum amount is the lesser of one-half of a participant's
   vested account balance or $50,000, reduced by the highest outstanding loan
   balance in a participant's account during the prior 12-month period.  Loans
   are fully secured by the participant's vested interest in his or her account.
   Loan terms generally range from one to 10 years.  Participant loans bear
   interest at a rate commensurate with local prevailing rates as determined
   quarterly by the Plan administrator.  The applicable interest rates for
   outstanding loans ranged from 7.5% to 9.5% as of December 31, 2000 and 1999.
   Principal and interest are paid ratably through semi-monthly payroll
   deductions.

2. SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES

   METHOD OF ACCOUNTING - The accompanying financial statements have been
   prepared on the accrual basis of accounting.  Purchases and sales of
   securities are recorded on a trade-date basis.  Dividends are recorded on the
   ex-dividend date.  Interest is recorded when earned.

   USE OF ESTIMATES - The preparation of financial statements in conformity with
   accounting principles generally accepted in the United States of America
   requires management to make estimates and assumptions that affect certain
   reported amounts and disclosures.  Accordingly, actual results may differ
   from those estimates.

   INVESTMENT VALUATION - Investments are stated at fair value based on quoted
   market prices.  Participant loans are stated at cost, which approximates fair
   value.

   EXPENSES - All expenses are paid by the Plan or the Company, as provided for
   in the Plan document.

   PAYMENT OF BENEFITS - Benefits are recorded when paid.

3. INVESTMENTS

   Investments representing five percent or more of the Plan's net assets as of
   December 31 are as follows:

                                                         2000         1999
                                                         ----         ----

      Fidelity Growth Company Fund                    $4,935,728   $2,976,055
      Fidelity Growth & Income Portfolio               3,373,840    1,671,617
      Fidelity Magellan Fund                           3,019,695    1,155,605
      Fidelity Retirement Money Market Portfolio       2,069,239      745,435
      Spartan U.S. Equity Index Fund                   2,059,015      969,910
      Fidelity Worldwide Fund                          1,567,018      712,939
      Fidelity Puritan Fund                            1,286,623      558,991

                                       7


3. INVESTMENTS (CONTINUED)

   During the years ended December 31, 2000 and 1999, the Plan's investments
   (including gains and losses on investments bought and sold, as well as held,
   during the year) (depreciated) appreciated in value as follows:

                                                        2000         1999
                                                        ----         ----

      Mutual funds                                  $(2,014,931)  $1,184,010
      Common stock                                       (9,753)          --
                                                    -----------   ----------

      Total                                         $(2,024,684)  $1,184,010
                                                    ===========   ==========


4. NONPARTICIPANT-DIRECTED INVESTMENTS

   At December 31, 2000 and 1999, the Plan had nonparticipant-directed
   investments representing loans to participants in the amount of $375,131 and
   $56,862, respectively.  The amount of interest income on loans for the years
   ended December 31, 2000 and 1999 was $10,168 and $2,755, respectively.

5. PLAN TERMINATION AND AMENDMENTS

   Although it has not expressed any intention to do so, the Board of Directors
   of the Company has the right under the Plan to suspend its contributions at
   any time and to terminate the Plan subject to the provisions set forth in
   ERISA.  In the event of any termination of the Plan, or upon complete or
   partial discontinuance of contributions, the accounts of each affected
   participant shall become fully vested.

   The Board of Directors of the Company also has the right to amend the Plan,
   in whole or in part, subject to the provisions of ERISA.  During 2000, the
   Plan was amended to (i) add Class A common stock of American Tower
   Corporation as an investment option, (ii) increase the Company's
   discretionary matching contribution to 35% of the first 5% of each employee's
   contribution for 2000, and (iii) exclude from the Plan the following classes
   of employees:  employees covered by a collective bargaining agreement, leased
   employees, nonresident aliens who do not receive any U.S. source income,
   independent contractors, seasonal employees, student interns, and employees
   under student cooperative programs.

6. TAX STATUS

   The Plan has not yet received a determination letter from the Internal
   Revenue Service regarding the Plan's compliance with the applicable
   provisions of the Internal Revenue Code (the "Code").  However, the Company
   believes that the Plan is currently designed and being operated in accordance
   with the provisions of the Code.  Accordingly, no provision for income taxes
   has been included in the Plan's financial statements.

7. RELATED-PARTY TRANSACTIONS

   The Plan's investments as of December 31, 2000 and 1999 include shares of
   mutual funds managed by Fidelity Management Trust Company, the plan trustee.
   In addition, investments include shares of common stock of American Tower
   Corporation, the plan sponsor.  These transactions qualify as party-in-
   interest transactions.

                                       8


8. RECONCILIATION OF FINANCIAL STATEMENTS TO FORM 5500

   The following is a reconciliation of net assets available for benefits in the
   accompanying financial statements to amounts reported in the Company's Form
   5500 at December 31, 2000 and 1999:

                                                       2000        1999
                                                       ----        ----

     Net assets available for benefits per the
      financial statements                         $20,570,104  $9,501,299
     Contributions receivable                         (725,052)   (461,892)
                                                   -----------  ----------

     Net assets available for benefits per the
      Form 5500                                    $19,845,052  $9,039,407
                                                   ===========  ==========


   The following is a reconciliation of contributions in the accompanying
   financial statements to amounts reported in the Company's Form 5500 for the
   years ended December 31, 2000 and 1999:

                                                       2000        1999
                                                       ----        ----

     Contributions per the financial statements    $11,887,049  $4,038,766
     Increase in contributions receivable             (263,160)   (275,242)
                                                   -----------  ----------

     Contributions per Form 5500                   $11,623,889  $3,763,524
                                                   ===========  ==========

9. SUBSEQUENT EVENT

   On June 15, 2001 the assets of the Kline Iron & Steel Company, Inc. 401(k)
   Profit-Sharing Plan of approximately $6.3 million were merged into the Plan.
   Kline Iron & Steel Company, Inc. is a wholly owned subsidiary of the Company.

                                  * * * * * *

                                       9


AMERICAN TOWER
RETIREMENT SAVINGS PLAN

SCHEDULE H, PART IV, LINE 4a - SCHEDULE OF NONEXEMPT TRANSACTIONS
YEAR ENDED DECEMBER 31, 2000
--------------------------------------------------------------------------------


                                                                            
a) Identity of             b) Relationship      c) Description           d) Purchase    e) Selling
   Party Involved             to Plan,             of Transactions,         Price          Price
                              Employer or          Including Maturity
                              Other Party-         Date, Rate of
                              in-Interest          Interest, Collateral,
                                                   Par or Maturity Value

American Tower Corporation*  Plan Sponsor         Timely deposit of        $-           $-
                                                  employee
                                                  loan repayments

American Tower Corporation*  Plan Sponsor         Timely deposit of        $-           $-
                                                  employee
                                                  contributions to the
                                                  Plan




                                              
f) Lease       g) Expenses           h) Cost of        i) Current
   Rental         Incurred              Asset             Value
                  in Connection                           of Asset
                  with
                  Transaction


 $-            $-                    $-                $  7,653  **



 $-            $-                    $-                $735,296  ***




*   Represents a party-in-interest to the Plan

**  Certain employee loan repayments, totalling $7,653, were inadvertently
    deposited to American Tower Corporation cash accounts and subsequently
    deposited to the Plan after the 15 business day period required by ERISA
    regulations.

*** Employee contributions, totalling $735,296, withheld from the August 2000
    payroll were deposited to the Plan on October 6, 2000. The deposit was not
    made within 15 business days, as required by ERISA regulations.

                                       10


AMERICAN TOWER
RETIREMENT SAVINGS PLAN

SCHEDULE H, PART IV, LINE 4i - SCHEDULE OF ASSETS HELD FOR INVESTMENT PURPOSES
AT END OF YEAR DECEMBER 31, 2000
--------------------------------------------------------------------------------


                                                                                            
                                               c) Description of Investment
                                                  Including Maturity Date,
            b) Identity of Issue, Borrower        Interest Rate, Collateral,                          e) Current
a)             Lessor or Similar Party            Par or Maturity Value                                  Value

*           Fidelity Investments               Growth Company Fund                                  $ 4,935,728
*           Fidelity Investments               Growth & Income Portfolio                              3,373,840
*           Fidelity Investments               Magellan Fund                                          3,019,695
*           Fidelity Investments               Spartan U.S. Equity Index Fund                         2,059,015
*           Fidelity Investments               Retirements Money Market Portfolio                     2,069,239
*           Fidelity Investments               Worldwide Fund                                         1,567,018
*           Fidelity Investments               Puritan Fund                                           1,286,623
*           Fidelity Investments               U.S. Bond Index Fund                                     730,979

*           American Tower Corporation         Common Stock                                             427,784

*           Participants                       Loans with various interest rates from 7.5%
                                               to 9.5% and various maturity dates through 2012          375,131
                                                                                                    -----------

            Total                                                                                   $19,845,052
                                                                                                    ===========


*  Represents a party-in-interest to the Plan.

                                       11




The Plan. Pursuant of requirements of the Securities Exchange Act of 1934, the
trustees (or other persons that administer the employee benefit plan) have duly
caused this annual report to be signed on behalf of the undersigned hereunto
duly authorized, in the city of Boston, Massachusetts on the 28th day of June
2001.

                                    AMERICAN TOWER RETIREMENT
                                     SAVING PLAN

                                    By: /s/ Justin D. Benincasa
                                    ---------------------------
                                    Justin D. Benincasa
                                    Senior Vice President and
                                    Corporate Controller


The following exhibits are filed as part of this Annual Report on Form 11-K.

Exhibit
Number                           Description
-------                                  --------------------------------
23.1                                     Consent of Deloitte & Touche LLP

Ex-23.1 OTHERDOC
    2
    0002.txt