Exhibit 21 ---------- SUBSIDIARIES OF AMERICAN TOWER CORPORATION Information is as of March 9, 2002. Jurisdiction of Subsidiary Incorporation or Organization - ---------- ----------------------------- 10 Presidential Way Associates, LLC (1) Delaware American Tower Corporation De Mexico S. de R.L. de C.V. Mexico American Tower Delaware Corporation Delaware American Tower do Brazil, Ltd. Brazil American Tower International, Inc. (2) Delaware American Tower Management Inc. Delaware American Tower PA LLC (3) Delaware American Tower Trust #1 Massachusetts Business Trust American Tower Trust #2 Massachusetts Business Trust American Tower, L.P. Delaware American Towers, Inc. Delaware ATC Connecticut, Inc. Delaware ATC GP, Inc. Delaware ATC Holding, Inc. Delaware ATC LP, Inc. Delaware ATC Midwest, LLC Delaware ATC MexHold, Inc. Delaware ATC Mexico Holding Corp. Delaware ATC Operating Inc. Delaware ATC Presidential Way, Inc. Delaware ATC Realty Holding, Inc. Delaware ATC South America Holding Corp. Delaware ATC Tower Services, Inc. New Mexico ATC Westwood, Inc. Delaware ATS-Needham LLC (4) Massachusetts ATS/PCS, LLC Delaware Flash Technology International, Inc. U.S. Virgin Islands Haysville Towers, LLC (5) Kansas Verestar Networks, Inc. (6) Delaware Kline Iron & Steel Co., Inc. Delaware Maritime Telecommunications Network, Inc. Colorado MATC Cellular, S. de R.L. de C.V. Mexico MATC Digital, S. de R.L. de C.V. Mexico MATC Servicios, S. de R.L. de C.V. Mexico MHB Tower Rentals of America LLC Mississippi MTS Wireless Components (S) PTE Ltd. Singapore New Loma Communications, Inc. California OmniAmerica Holdings Corporation Delaware OmniAmerica Towers, Inc. Delaware Shreveport Tower Company Louisiana Telecom Towers, LLC Delaware Towers of America LLLP Delaware Towersites Monitoring, Inc. Delaware UniSite/Omni Point NE Tower Venture, L.L.C. (7) Delaware UniSite/OmniPoint FL Tower Venture, L.L.C. (8) Delaware UniSite/OmniPoint PA Tower Venture L.L.C. (9) Delaware Unisite, Inc. Delaware Verestar AG Switzerland Verestar International, Inc. Delaware Verestar, Inc. Delaware - -------- (1) 83.4105% owned by ATC Presidential Way, Inc. (2) Formerly known as ATC International Holding Corp. (3) Formerly known as American Tower Texas LLC. (4) 45.23% owned by American Tower, LP and 34.77% owned by American Towers, Inc. (5) 67% owned by Telecom Towers, LLC. (6) Formerly known as Interpacket Networks, Inc. (7) 95% owned by Unisite, Inc. (8) 95% owned by Unisite, Inc. (9) 95% owned by Unisite, Inc.