Domes soar to great heights and span vast spaces–their inspiring form is reserved for society’s greatest buildings. The Capitol’s iron dome, an instantly recognizable American symbol, has long been admired for its majestic beauty and its ingenious engineering.
A Key to the Dome
This image is a composite of two 1859 drawings by Thomas U. Walter showing the final dome design. Both drawings are in the records of the Architect of the Capitol.
Designed by Thomas U. Walter, the dome was influenced by classical European domes, such as St. Paul’s in London, St. Isaac’s in St. Petersburg, and the Panthéon in Paris. Capt. Montgomery C. Meigs of the U.S. Army Corps of Engineers supervised much of its construction. It was especially challenging to build because it replaced an existing wooden dome (completed by Charles Bulfinch in 1824), but re-used the old rotunda walls as foundations.
Technical difficulties were easy to overcome compared to those of the Civil War, which broke out just six years after the new dome was begun. When the contractors continued installing ironwork despite wartime conditions, President Abraham Lincoln viewed the rising dome as a sign that the Union would continue as well.
Facts About the Dome
Authorized by Congress March 3, 1855 Begun September 1855 - Finished January 1866 Architect: Thomas U. Walter
Cost: $1,047,291 Weight of ironwork: 8,909,200 pounds Number of windows: 120 Number of columns: 48
Exterior Height: 217 feet from the base of the dome to the top of the statue; 288 feet from the ground to the top of the statue
Interior Height: 180 feet from the rotunda floor to the to the top of the interior dome