The Pentagon in Washington DC is the largest office building in the world and serves at the headquarters for the Defense Department. It is twice the size of the Merchandise Mart in Chicago, and has three times the floor space of the Empire State Building in New York. Built during the early years of World War II, it is still thought of as one of the most efficient office buildings in the world. Despite 17.5 miles of corridors it takes only seven minutes to walk between any two points in the building.
When used in the media, the term "Pentagon" has come to mean the bureaucracy of the Department of Defense.