The red granite building features a cast-iron dome similar to the one at the National Capitol in Washington.

Congress votes to replace Bulfinch's wooden/copper dome with cast-iron dome designed by Walter; Constantino Brumidi paints first fresco in the Capitol.

Below the cast-iron dome, the ceiling displays eight muses painted in 1886.

The room was completed in 1859 as part of the Capitol's vast extension, which added new Senate and House wings and the new cast-iron dome.

Walter also designed a new cast-iron dome, which was authorized in 1855.

A monumental statue for the top of the national Capitol appeared in architect Thomas U. Walter's original drawing for the new cast-iron dome, which was authorized in 1855.

Instead the drawing showed a new cast-iron dome with columns, pilasters, brackets, scores of windows, and a crowning statue.

The Capitol's cast-iron dome was designed in 1854 by Thomas U. Walter, the fourth Architect of the Capitol, who had also designed the building's north and south extensions.

There it was placed on the simple, velvet-covered wood catafalque first used at Abraham Lincoln's funeral in 1865, 180 feet below the concave ceiling of the Capitol's cast-iron dome.

As work progressed, Walter also designed a new cast-iron dome to better suit the enlarged building.