The United States Capitol building features a central rotunda below the Capitol dome. Built between 1818 and 1824, the rotunda has been described as the Capitol's "symbolic and physical heart".

The United States Capitol, often called the Capitol or the Capitol Building, is the seat of the United States Congress, the legislative branch of the federal government. It is located on Capitol Hill at the eastern end of the National Mall in Washington, D.C. Although no longer at the geographic center of the national capital, the U.S. Capitol forms the origin point for the street-numbering system of the district as well as its four quadrants.