The Old Post Office, listed on the National Register of Historic Places as the Old Post Office and Clock Tower, is located at 1100 Pennsylvania Avenue, N.W. in Washington, D.C. It is a contributing property to the Pennsylvania Avenue National Historic Site. It is adjacent to the Federal Triangle station on the Washington Metro. The building's 315-foot (96-meter) high clock tower houses the "Bells of Congress," and its observation level offers panoramic views of the city and its surroundings. A historic federal office building, it now serves as a hotel.
Construction began in 1892 and was completed in 1899. The building is an example of Richardsonian Romanesque architecture, popular in the late 19th-century United States.