A White House performer at the bottom of the staircase from the ground floor hall, 2008 (Bob and Cherrie)
The White House Sub-Basement is not original to the structure. It was dug during the Truman reconstruction in 1949, and staircases off the Center Hall on the east side were built in space formerly occupied by larger lavatories off the Library and Vermeil Room. These staircases have small windows that open into window nooks on the east side.
The Sub-Basement contains much of the mechanical necessities of the White House. There are likely two separate sub-basement levels under the White House. Just off the stairs down are dressing rooms for guests who come to the White House to perform.
White House performers in a dressing room, 2008 (Bob and Cherrie)
The north basement staircase down from the Center Hall in 1992 (HABS)
The sub-basement staircase down from the Center Hall in 1952 (Truman Library)