The United States Capitol Dome may well be the most famous man-made landmark in America. It is such a fitting finale for the building it crowns, so familiar and dignified, that it seems surprising that its design and construction came late in the U.S. Capitol's architectural evolution. Only the West Front terraces (1884-1892), the East Front extension (1958-1962), and the Capitol Visitor Center are more recent additions to the U.S. Capitol than its dome (1856-1866). It was designed by the Philadelphia architect Thomas U. Walter, who was also the architect of the House and Senate extensions.