Designed by architect George Bergstrom, The Pentagon was dedicated on January 15, 1943.
It is the highest-capacity office building in the world and one of the world's largest buildings in terms of floor area.
The open space in the center is informally known as "ground zero," a nickname originating during the Cold War when it was thought by the Soviet Union to be a top-secret area or command center, understandable, it being centrally located, and with a massive amount of traffic compared to the rest of the Pentagon when seen with a spy satellite. At the center of this plaza is the "Ground Zero Cafe," a snack bar.
Ground was broken for the Pentagon on September 11, 1941, with construction completed in approximately sixteen months at a cost of $83 million.
Its unusual shape results from the fact that its originally intended site, Arlington Farms, fronted on Arlington Ridge Road and the Arlington Memorial Bridge approach, which intersected at an angle of approximately 108 degrees (the angle of a regular pentagon).
A minimal amount of steel was used in construction, which was in short supply during World War II. 680,000 tons of sand, dredged from the Potomac River, were used in the reinforced concrete structure.
Despite 17.5 miles of corridors it takes only seven minutes to walk between any two points in the building.