United States Capitol crypt

The United States Capitol crypt is the large circular room filled with forty neoclassical Doric columns directly beneath the United States Capitol rotunda. It was built originally to support the rotunda as well as offer an entrance to Washington's Tomb. It currently serves as a museum and a repository for thirteen statues of the National Statuary Hall Collection.

The crypt originated with the initial designs drawn up for the United States Capitol by William Thornton, which called for a rotunda to be placed between the two wings of the building. The room beneath the rotunda was therefore required to support the large space above it. However, construction did not begin on the central part of the Capitol, where the rotunda and the room beneath it were located, until after the War of 1812.

Construction on the Capitol itself began in 1793, when the first American President, George Washington, laid down the cornerstone to the north wing of the building. Upon the death of Washington in 1799, the designers of the Capitol went to Martha Washington and requested permission to build a tomb for her husband in the Capitol. She acquiesced to this request and plans were made to construct the tomb underneath the floor that supported the rotunda. This area was designated the crypt, as it would serve as the entry to the tomb.

Delays wracked the construction efforts of the Capitol's builders, notably the interruption by the War of 1812, when all construction came to a halt. In August 1814, the British captured the city of Washington and set fire to the Capitol, nearly destroying the entire building. Thus, when construction recommenced after the war ended in 1815, it was initially to rebuild what had been lost to the fire.

...
Wikipedia