AMENDMENT TO CONTRIBUTION AGREEMENT

Exhibit 10.4

AMENDMENT TO

CONTRIBUTION AGREEMENT

(Republic Square I)

THIS AMENDMENT TO CONTRIBUTION AGREEMENT is entered into as of December 20, 2005 by and among REPUBLIC PROPERTIES CORPORATION, a District of Columbia corporation (“ RPC ”), REPUBLIC PROPERTY LIMITED PARTNERSHIP, a Delaware limited partnership (the “ Operating Partnership ”), and 25 Massachusetts Avenue Property LLC, a Delaware limited liability company (“ 25 Mass ”).

WHEREAS, the Operating Partnership, RPC and 25 Mass previously entered into that certain Contribution Agreement dated as of September 23, 2005 (the “ Contribution Agreement ”); and

WHEREAS, the Operating Partnership, RPC and 25 Mass desire to amend certain terms of the Contribution Agreement.

NOW THEREFORE, in consideration of the foregoing and the mutual covenants and conditions set forth herein and othe