Executive Residence

The Executive Residence is the central building of the White House complex located between the East Wing and West Wing. It is the most recognizable part of the complex, being the actual "house" part of the White House. This central building, first constructed from 1792 to 1800, is home to the President of the United States and the First Family. The Executive Residence primarily occupies four floors: the Ground Floor, the State Floor, the Second Floor, and the Third Floor. A two-story sub-basement with mezzanine, created during the 1948–to-1952 Truman reconstruction, is used for HVAC and mechanical systems, storage, and service areas.

This level was added during the 1948-to-1952 renovation, and contains the air conditioning and water softening equipment. The sub-basement and mezzanine also contain storage areas, the heating system, elevator machinery rooms, an incinerator, a medical clinic, a dentist's office, the electrical control system, a laundry room, and flatware and dishware storage.

The Ground Floor of the White House originally contained service rooms. The White House is built on a slight hill that slopes to the south. To provide access to the north side of the Ground Floor, the area around the north side of the mansion and its northeast and northwest corners was excavated to provide light and air to this half of the Ground Floor. Architect James Hoban designed the Ground Floor so that the kitchen was directly beneath the Entrance Hall, the door to the kitchen below the North Portico. Storerooms were east of the kitchen, while a toilet and dishwashing room were to the west. The kitchen was relocated into the two rooms in the northwest corner of the Ground Floor by 1846, while the old kitchen space as transformed into an informal sitting room/reception space. As of 2010, this large central space originally occupied by the kitchen in the early 1800s had been subdivided into offices for the White House Curator and the United States Secret Service. The kitchen, too, continues to occupy the three rooms (somewhat altered in size now) in the northwest corner of the Ground Floor.

...
Wikipedia