Old Post Office

The Old Post Office Pavilion is located the intersection of 12th Street and Pennsylvania Avenue, NW, in Washington, DC. Its strong arches, squat columns, and 315 ft-high tower make it the third tallest structure and the last major example of Richardsonian Romanesque architecture in the District of Columbia. Scarcely used as a post office, it has been rehabilitated today into office and retail space shared by the federal government and private businesses. The expansive interior atrium is now home to shops, entertainment space, and a food court.

More info at  en.wikipedia.org