The Pentagon

The Pentagon
A view of The Pentagon from above the Potomac River in 2018
General information
Architectural style	Classical Revival, Modern, and Stripped Classicism
Location	Richmond Hwy./VA 110 at I-395, Arlington County, Virginia, U.S.
Coordinates	38°52′15″N 77°03′18″W / 38.87083°N 77.05500°W / 38.87083; -77.05500
Construction started	11 September 1941 (1941-09-11)
Completed	15 January 1943 (1943-01-15)
Cost	$83 million (equivalent to $1.33 billion in 2023)[1]
Owner	United States Department of Defense
Height
Roof	77 ft (23 m)[2]
Dimensions
Other dimensions	Sides: 5 (1943-2001) 4 (2001-2002) 5 (2002-present)
Technical details
Floor count	7 (2 underground)
Floor area	6,636,360 sq ft (620,000 m2)
Design and construction
Architect(s)	George Bergstrom David J. Witmer
Main contractor	John McShain, Inc.
Other information
Parking	67 acres (27 ha)
Pentagon Office Building Complex
U.S. National Register of Historic Places
Virginia Landmarks Register
NRHP reference No.	89000932[3]
VLR No.	000-0072
Significant dates
Added to NRHP	27 July 1988
Designated VLR	18 April 1989[4]

The Pentagon is the headquarters building of the United States Department of Defense, in Arlington County, Virginia, across the Potomac River from Washington, D.C. The building was constructed on an accelerated schedule during World War II. As a symbol of the U.S. military, the phrase The Pentagon is often used as a metonym for the Department of Defense and its leadership.

The building was designed by American architect George Bergstrom and built by contractor John McShain. Ground was broken on 11 September 1941, and the building was dedicated on 15 January 1943. General Brehon Somervell provided the major impetus to gain Congressional approval for the project;^[5] Colonel Leslie Groves was responsible for overseeing the project for the U.S. Army Corps of Engineers, which supervised it.

The Pentagon is the world's second-largest office building, with about 6.5 million square feet (600,000 m²) of floor space, 3.7 million square feet (340,000 m²) of which are used as offices.^[6][7] 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)^[7] of corridors, with a central five-acre (2.0 ha) pentagonal plaza. About 23,000 military and civilian employees work in the Pentagon, as well as about 3,000 non-defense support personnel.^[7]

In 2001, the Pentagon was damaged during the September 11 attacks. Five Al-Qaeda hijackers flew American Airlines Flight 77 into the western side of the building, killing themselves and 184 other people, including 59 on the airplane and 125 in the Pentagon.^[8] It was the first significant foreign attack on federal facilities in the capital area since the burning of Washington during the War of 1812.^[9] Following the attacks, the western side of the building was repaired, with a small indoor memorial and chapel added at the point of impact. The coordinated attacks, which killed 2,977 people, were the deadliest terrorist attack in history.

In 2009, an outdoor memorial dedicated to the Pentagon victims of the September 11 attacks was opened directly southwest of the Pentagon.