PENTAGON

large five-sided building in Arlington county, Va., near Washington, D.C., that serves as headquarters of the U.S. Department of Defense, including all three services-Army, Navy, and Air Force. Designed by George Edwin Bergstrom, it was built in 1941-43 to bring under one roof the U.S. War Department offices then housed in widely scattered buildings. On its completion it was the world's largest office building, covering 34 acres (14 hectares; including a 5-acre [2-hectare] central court) and offering 3,700,000 square feet (343,730 square m) of usable floor space for as many as 25,000 persons, military and civilian. Built of structural steel and reinforced concrete with some limestone facing, the structure has five floors, excluding the mezzanine and the basement. The building consists of five concentric pentagons, or "rings," with 10 spokelike corridors connecting the whole. A huge concourse within it provides a shopping centre for Pentagon workers, and beneath this concourse are bus and taxi terminals. Parking areas adjacent to the building can accommodate as many as 10,000 cars, and a heliport for the Pentagon was added in 1956. Additional reading