The nation's 100 senators sit at individual desks arranged on a tiered semicircular platform facing a raised rostrum. A visitor's gallery overlooks the chamber on four sides.
The Senate met in a semicircular room of the U.S. Capitol's north wing from 1819 until this new chamber was ready in 1859. First used on January 4, 1859, the Senate chamber was designed by Thomas U. Walter, the architect of the Capitol extension. The chamber was built without windows to insulate senators from outside noise. Light was originally provided through a large skylight and ventilation came courtesy of steam-powered fans.
In 1949-1950, the chamber was reconstructed, the skylight removed and the walls redesigned. Pilasters made from red Levanto marble replaced the cast-iron originals; the wooden rostrum was replaced with a larger version in marble; and the iron and glass ceiling was taken out and a new stainless steel and plaster ceiling installed. The alteration were intended to improve the chamber's acoustics and ventilation while ridding it of its mid 19th-century decor, which was then out of fashion.