Exhibit 21.1 Beacon Capital Partners, Inc. Fed ID Name Number OPERATING ENTITIES Beacon Capital Partners, Inc. 04-3403281 Beacon Capital Partners, L.P. 04-3411475 Beacon Capital Partners 04-3401623 Beacon Venture Partners, Inc. 04-3415691 Beacon Venture Partners, L.P. 04-3415684 Beacon Capital Participation Plan, L.P. 04-3415681 Beacon Capital Participation Plan, LLC 04-3415697 Beacon Capital Partners Management, LLC 04-3415676 Beacon Capital Partners Acquisition, LLC 04-3415563 Cambridge Kendall SPC, Inc. 04-3415687 Cambridge Athenaeum, LLC 04-3418134 Kendall Athenaeum, LLC 04-3418136 One Kendall, LLC 04-3418137 Beacon/PW Kendall LLC 04-3418140 Technology Square LLC 04-3422723 Dallas Office Portfolio, L.P. 04-3424722 Suburban Dallas Office Portfolio, LLC 04-3424723 Sunnyvale Investments LLC 04-3430638 Columbia Street LLC 04-3432695