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 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.