United States Capitol - Cast-Iron Dome (1855–1866)

The current cast-iron dome of the United States Capitol was constructed between 1855 and 1866 under Architect Thomas U. Walter, replacing an earlier wooden dome. The dome was cast in iron and the Statue of Freedom was placed atop it in 1863 during construction. The iron dome substantially altered the Capitol's silhouette and remains a defining element of the building's neoclassical design.