The Old Post Office Pavilion, also known as Old Post Office and Clock Tower and officially renamed the Nancy Hanks Center in 1983, is a building of the United States federal government. Built in 1892-99, it is located at 1100 Pennsylvania Avenue (the intersection of 12th Street and Pennsylvania Avenue), NW, in Washington, D.C. Its rustication, strong semi-circular arches, squat clustered columns united by a foliate Sullivanesque capital-frieze, make it the last major example of Richardsonian Romanesque architecture to be constructed in the District of Columbia. Its 315 ft (96 m)-high clocktower makes the building the largest commercial building and the third tallest structure in Washington D.C. 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, federal offices, entertainment space and a food court.
National Park Service rangers from Pennsylvania Avenue National Historic Site provide tours of the Old Post Office Tower affording one of the most spectacular views of Washington from its 270-foot (82 m)-high observation deck. The tower includes an exhibit room depicting the building's long struggle for survival. Visitors can also view the Bells of Congress, replicas of those at Westminster Abbey and given by the Ditchley Foundation to the United States in 1983 to celebrate the bicentennial of the end of the Revolutionary War. The Washington Ringing Society sounds The Bells of Congress every Thursday evening and on special occasions. The official bells of the United States Congress, they are one of the largest sets of change ringing bells in North America. Free tours of The Old Post Office Pavilion Colck Tower are offered daily. More information is available by calling (202) 606-8691.