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The Capitol Dome

 

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.
 
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.
  • 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

    Facts About the Dome

  • The Statue of Freedom was sculpted in Rome by the American artist Thomas Crawford. Upon learning of the statue’s final height, architect Thomas U. Walter redesigned the dome, lowering it to accommodate the 19½-foot bronze sculpture and creating an inner dome with a canopy to hold a fresco by Constantino Brumidi.

    The Statue of Freedom

  • Designed by sculptor Thomas Crawford, the cast-iron pedestal is painted to match the bronze of the statue. It is encircled with the motto, "E Pluribus Unum," which means "Out of Many, One."

    Pedestal

  • Topping the dome, this temple-like structure houses lights that shine only when Congress is in evening session. The observation platform at the base of the tholos is approximately 210 feet above the Capitol’s east front plaza.

    Tholos

  • Constantino Brumidi's fresco was created by applying pigment to fresh plaster laid in sections on a bowl-shaped canopy suspended 180 feet above the rotunda floor. Covering 4,664 square feet, it was painted in 1865 over a period of 11 months.

    The Apotheosis of Washington

  • The drum is two stories high and provides visual and structural support for the cupola and statue. Thirty-six columns ring the drum's lower story.

    The Drum

  • The Capitol actually has two domes. The outer dome was scaled to the size of the exterior of the building, whereas the smaller interior dome is sized to the rotunda’s proportions. Thirty-six iron trusses support both domes.

    Inner Dome

  • The frescoed frieze, which traces America's history from the landing of Columbus to the birth of aviation, was painted to give the illusion of a carved stone relief. Scenes designed and painted by Constantino Brumidi were completed after his death by Filippo Costaggini. The last three scenes were designed and painted by Allyn Cox in 1953.

    The Rotunda Frieze

  • The base, or skirt, provides the dome with a visual foundation. Behind the skirt are the 72 paired brackets that support the columns of the lower story of the drum.

    Base