The United States Capitol is the capitol building that serves as the seat of government for the United States Congress, the legislative branch of the U.S. federal government. It is located in Washington, D.C., on top of Capitol Hill at the east end of the National Mall. Although not in the geographic center of the District of Columbia, the Capitol is the focus by which the quadrants of the district are divided. Officially, the east and west sides of the Capitol are referred to as "fronts." Historically, however, the east front was initially the side of the building intended for the arrival of visitors and dignitaries.

The building was originally designed by William Thornton. This plan was subsequently modified by Stephen Hallet, Benjamin Latrobe and then Charles Bulfinch. The current dome and the House and Senate wings were designed by Thomas U. Walter and August Schoenborn, a German immigrant, and were completed under the supervision of Edward Clark.

The building is marked by its central dome above a rotunda and two wings, one for each chamber of Congress: the north wing is the Senate chamber and the south wing is the House of Representatives chamber. Above these chambers are galleries where visitors can watch the Senate and House of Representatives. It is an example of the Neoclassical architecture style. The statue on top of the dome is the Statue of Freedom.