United States Capitol dome

The origin of the first dome began with the Capitol design contest sponsored by Secretary of State Thomas Jefferson, at the behest of President George Washington, in 1792.

The third Architect of the Capitol, Charles Bulfinch, altered the exterior profile of the plans still further by increasing the dome's height, which he later wrote was at the insistence of the President and Congress.

Set at the crown of the exterior dome was an oculus 24 feet (7.3 m) wide, which provided illumination to the rotunda floor below.

Under the guidance of the fourth Architect of the Capitol, Thomas U. Walter, extensions were built onto the north and south wings of the building.

In the process, the new, longer building made the original Bulfinch dome appear aesthetically displeasing (and it had in any case been the object of much prior criticism).

Congress, after lobbying by Walter and Montgomery C. Meigs, then the supervising engineer, passed legislation to build a bigger dome in 1855.

[10] Influenced by the great domes of Europe, Walter paid particular attention to the Pantheon of Paris, St Paul's Cathedral in London and St. Peter's Basilica in Rome, as well as the more recent Saint Isaac's Cathedral in Saint Petersburg, Russia, one of the first domes with an iron frame, by Auguste de Montferrand (1786–1858).

Crowning the composition was a statue standing on a slender, columned tholus ...[12]Walter drafted a seven-foot (2.1 m) drawing of the aforementioned design and displayed it in his office, where it drew the excited attention of members of Congress in 1854.

[14] Construction began after some practical changes to the original design (such as the reduction of the columns from 40 to 36) in September of that year with the removal of the dome raised by Charles Bulfinch.

A unique scaffold was built inside the rotunda, designed to keep weight away from the weak center area of the floor, and a crane was set within to run on a steam-powered engine (fueled from the salvaged wood from the old dome).

This was not accomplished until after Walter had been forced to revise the design of the dome to handle the statue, which had been delivered taller and heavier than requested.

Just over a month later, in January 1866, Constantino Brumidi—who had been hired to paint a fresco on a platform above the interior dome's oculus—removed the scaffolding used during his work on the Apotheosis of Washington.