The Executive Residence is the central and most recognizable part of the White House complex, being the actual "house" part of the White House. This central building is home to the president of the United States and the first family. The Executive Residence was first constructed from 1792 to 1800. It primarily occupies four floors: the ground floor, the state floor, the second floor, and the third floor. The third floor was created in 1927 from attic space. A sub-basement with a mezzanine, created during the 1948–1952 Truman Reconstruction, is used for HVAC and mechanical systems, storage, and service areas.