The floor area of this five-sided building (1943) is twice that of the Empire State Building. The number of escalators, stairs and toilets is equally huge and the length of the corridors adds up to kilometres! The guided tour of the building, which houses the military and defence authorities, tells you more about the wars the United States has been involved in, and passes through the Hall of Heroes. Outside, there is a memorial at the site where American Airlines Flight 77 crashed on 11 September 2001.