Pentagon building

The Pentagon
The Pentagon in January 2008
Location in the Washington, D.C. area
Information General information Status Complete Architectural style Stripped Classicism Location Arlington County, Virginia Address 1400 Defense Pentagon, Washington, DC 20301-1400 Coordinates 38°52′16″N 77°03′21″W / 38.87099°N 77.05596°W / 38.87099; -77.05596 Construction started September 11, 1941; 75 years ago (1941-09-11) Completed January 15, 1943; 74 years ago (1943-01-15) Cost $83 million ($1.35 billion in 2016 dollars) Owner United States Department of Defense Height Roof 77 feet 3.5 inches (23.559 m) Top floor 5 Technical details Floor count 7 Floor area 6,636,360 square feet (620,000 m2) Design and construction Architect George Bergstrom David J. Witmer Main contractor John McShain, Inc. Other information Parking 67 acres References Pentagon Office Building Complex U.S. National Register of Historic Places Virginia Landmarks Register Show map of Virginia Show map of the US Location Jefferson Davis Hwy./VA 110 at I-395, Arlington, Virginia Area 41 acres (17 ha) Built 1941 (1941) Architect Bergstrom, G.E.; Witmer, D.J. Architectural style Classical Revival, Modern Movement, Stripped Classicism NRHP Reference # 89000932 VLR # 000-0072 Significant dates Added to NRHP July 27, 1988 Designated VLR April 18, 1989

The Pentagon is the headquarters of the United States Department of Defense, located in Arlington County, Virginia, across the Potomac River from Washington, D.C. As a symbol of the U.S. military, The Pentagon is often used metonymically to refer to the U.S. Department of Defense.

The Pentagon was designed by American architect George Bergstrom (1876–1955), and built by general contractor John McShain of Philadelphia. Ground was broken for construction on September 11, 1941, and the building was dedicated on January 15, 1943. General Brehon Somervell provided the major motive power behind the project; Colonel Leslie Groves was responsible for overseeing the project for the U.S. Army.

The Pentagon is one of the world's largest office buildings, with about 6,500,000 sq ft (600,000 m²), of which 3,700,000 sq ft (340,000 m²) are used as offices. Approximately 23,000 military and civilian employees and about 3,000 non-defense support personnel work in the Pentagon. It has five sides, five floors above ground, two basement levels, and five ring corridors per floor with a total of 17.5 mi (28.2 km) of corridors. The Pentagon includes a five-acre (20,000 m²) central plaza, which is shaped like a pentagon and informally known as "ground zero," a nickname originating during the Cold War on the presumption that it would be targeted by the Soviet Union at the outbreak of nuclear war.

On September 11, 2001, exactly 60 years after the building's construction began, American Airlines Flight 77 was hijacked and flown into the western side of the building, killing 189 people (59 victims and the five perpetrators on board the airliner, as well as 125 victims in the building), according to the official report. It was the first significant foreign attack on Washington's governmental facilities since the city was burned by the British during the War of 1812.