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The Pentagon
Arlington County, Virginia
Southwest view of the Pentagon with the Potomac River and Washington Monument in background (1998).
Type Headquarters
Height Five floors above ground and two floors below ground
In use 1943–present
In Service
United States Department of Defense Wikipedia
Controlled by U.S. Secretary of Defense


The Pentagon is the headquarters of the United States Department of Defense, located in Arlington County, Virginia. As a symbol of the U.S. military, "the Pentagon" is often used metonymically to refer to the Department of Defense rather than the building itself.

Designed by the American architect George Bergstrom Wikipedia, and built by Philadelphia, Pennsylvania, general contractor John McShain Wikipedia, the building was dedicated on January 15, 1943, after ground was broken for construction on September 11, 1941. General Brehon Somervell Wikipedia provided the major motive power behind the project;[1] Colonel Leslie Groves Wikipedia was responsible for overseeing the project for the Army.

The Pentagon is the world's largest office building by floor area, with about 6,500,000 sq ft (Template:Rnd/c6dec0 m2), of which 3,700,000 sq ft (340,000 m2) are used as offices.[2][3] Approximately 23,000 military and civilian employees[3] and about 3,000 non-defense support personnel work in the Pentagon. It has five sides, five floors above ground (plus two basement levels), and five ring corridors per floor with a total of 17.5 mi (28.2 km)[3] 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 Wikipedia and based on the presumption that the Soviet Union Wikipedia would target one or more nuclear missiles at this central location in the outbreak of a nuclear war.[citation needed]

On September 11, 2001, exactly 60 years since the building's groundbreaking, hijacked American Airlines Flight 77 was crashed into the western side of the Pentagon, killing 189 people, including five hijackers, 59 others aboard the plane, and 125 working in the building.[4]

File:Pentagon road network map 1945.jpg

Construction and historyEdit

Part 1Edit

Government officials agreed that the War Department building should be constructed across the Potomac River, in Arlington, Virginia. Requirements for the new building were that it be no more than four stories tall, and that it use a minimal amount of steel. The requirements meant that instead of rising vertically, the building would be sprawling over a large area. Possible sites for the building included Arlington Farm, adjacent to Arlington National Cemetery Wikipedia, and the obsolete Washington Hoover Airport site.[5] The Pentagon shape of the building was a result of the shape of Arlington Farms, which was the site originally chosen,[6] however President Roosevelt ended up selecting the Hoover Airport site, as he did not want the new building to obstruct the view of Washington, D.C. from Arlington Cemetery.[7] But the building retained its pentagonal shape, because a major redesign at that stage would have been costly and because Roosevelt liked the design. Freed of the constraints of the asymmetric Arlington Farms site, however, it was modified into a regular pentagon.[8][9]

Part 2Edit

On July 28, Congress authorized funding for a new Department of War building in Arlington, which would house the entire department under one roof,[10] and President Roosevelt officially approved of the Hoover Airport site on September 2.[11] While the project went through the approval process in late July 1941, Somervell selected the contractors, including John McShain, Inc. of Philadelphia, which had built Washington National Airport in Arlington, the Jefferson Memorial in Washington, and the National Naval Medical Center in Bethesda, Maryland, along with Wise Contracting Company, Inc. and Doyle and Russell — both from Virginia.[12] In addition to the Hoover Airport site and other government-owned land, construction of the Pentagon required an additional 287 acres (1.16 km2), which were acquired at a cost of $2.2 million.[13] The Hell's Bottom neighborhood, a slum with numerous pawnshops, factories, approximately 150 homes, and other buildings around Columbia Pike, was also cleared to make way for the Pentagon.[14] Later on, Template:Convert/LoffAonDbSoffNa of land were transferred to Arlington National Cemetery and to Fort Myer, leaving Template:Convert/LoffAonDbSoffNa for the Pentagon.[13]

File:Pentagon construction.jpg

Contracts totaling $31,100,000 were finalized with McShain and the other contractors on September 11, and ground was broken for the Pentagon the same day.[15] Among the design requirements, Somervell required the structural design to accommodate floor loads of up to 150 pounds per square foot, which was done in case the building became a records storage facility at some point in the future, after World War II.[11] A minimal amount of steel was used in construction, which was in short supply during World War II. Instead, the Pentagon was built as a reinforced concrete structure, using 680,000 tons of sand, dredged from the Potomac River, and a lagoon was created beneath the Pentagon's river entrance. To minimize steel, concrete ramps were built rather than installing elevators.[16][17] Indiana limestone was used for the building's facade.[18]

Architectural and structural design work for the Pentagon proceeded simultaneously with construction, with initial drawings provided in early October 1941, and most of the design work completed by June 1, 1942. At times, the construction work got ahead of the design, with different materials used than what was specified in the plans. Pressure to speed up design and construction intensified after the Attack on Pearl Harbor, on December 7, 1941, with Somervell demanding that 1,000,000 sq ft ({{rnd/bExpression error: Unexpected < operator.|Expression error: Unexpected < operator.|(Expression error: Unexpected < operator.)|Expression error: Unexpected < operator. }} ha) of space at the Pentagon be available for occupation by April 1, 1942.[19] David J. Witmer replaced Bergstrom as chief architect on April 11, after Bergstorm resigned due to charges, unrelated to the Pentagon project, of improper conduct while he was president of the American Institute of Architects.[20]

The soil conditions of the Pentagon site, located on the Potomac River floodplain, presented challenges to engineers, as did the varying elevations across the site, which ranged from Template:Convert/Dual/LoffAonDbSoff above sea level. Two retaining walls were built to compensate for the elevation variations, and cast-in-place (Franki) piles were used to deal with the soil conditions.[21] Construction of the Pentagon was completed in approximately 16 months at a total cost of $83 million. The building is 77 feet (23 m) tall. Each of the five sides of the building are 921 feet (281 m) long. [22]


Main article: Pentagon Renovation Program

Since 1998, the Pentagon has been undergoing a major renovation, known as the Pentagon Renovation Program. This program, scheduled to be completed in 2010, involves the complete gutting and reconstruction of the entire building in phases to bring the building up to modern standards, removing asbestos, improving security and providing greater efficiency for Pentagon tenants. Recently, the process of sealing all of the building's windows began.

As originally built, most Pentagon office space consisted of open bays which spanned an entire ring. These offices used cross-ventilation from operable windows instead of air conditioning for cooling. Gradually, bays were subdivided into private offices with many using window air conditioning units. When renovations are completed, the new space will include a return to open office bays, with a new Universal Space Plan of standardized office furniture and partitions developed by Studios Architecture.[23]

September 11 attacksEdit

Main article: American Airlines Flight 77
Main article: Attack on the Pentagon
File:Pentagon video security4.jpg
Pentagon blue lights

9/11 anniversary illumination

On September 11, 2001, a team of five al-Qaeda affiliated hijackers took control of American Airlines Flight 77, en route from Washington Dulles International Airport to Los Angeles International Airport, and deliberately crashed into the Western side of the Pentagon at 9:37 a.m. EDT as part of the September 11 attacks. All 64 people on the airliner were killed as were 125 people who were in the building. The impact of the plane severely damaged the structure of the building and caused its partial collapse.[25] At the time of the attacks, the Pentagon was under renovation and several offices were unoccupied, resulting in fewer casualties. Only 800 of 4500 people who would have been in the area were there because of the work. But the area hit, on the side of the Heliport Entrance facade, was the section best prepared for such an attack. The renovation there, improvements which resulted from the Oklahoma City bombing Wikipedia, had nearly been completed.[26][27][28]

It was the only area of the Pentagon with a sprinkler system, and it had been reconstructed with a web of steel columns and bars to withstand bomb blasts. The steel reinforcement, bolted together to form a continuous structure through all of the Pentagon's five floors, kept that section of the building from collapsing for 30 minutes—enough time for hundreds of people to crawl out to safety.

The area struck by the plane also had blast-resistant windows—2 inches thick and 2,500 pounds each—that stayed intact during the crash and fire. It had fire doors that opened automatically and newly built exits that allowed people to get out.[26]

Contractors already involved with the renovation were given the added task of rebuilding the sections damaged in the attacks. This additional project was named the "Phoenix Project", and was charged with having the outermost offices of the damaged section occupied by September 11, 2002.[29][30][31]

When the damaged section of the Pentagon was rebuilt, a small indoor memorial and chapel were included, located at the point of impact. For the fifth anniversary of the September 11, 2001 attacks, a memorial of 184 beams of light shone up from the center courtyard of the Pentagon, one light for each victim of the attack. In addition, an American flag is hung each year on the side of the Pentagon damaged in the attacks, and the side of the building is illuminated at night with blue lights. After the attacks, plans were developed for an outdoor memorial, with construction underway in 2006. The Pentagon Memorial, which consists of a Template:Convert/LoffAonDbSoffNa park with 184 benches, according to the victims' ages, from 3 to 71, was opened to the public on September 11, 2008.[32][33][34]


The Pentagon building spans Template:Convert/LoffAonDbSoffNa, and includes an additional Template:Convert/LoffAonDbSoffNa as a central courtyard.[35] It has five façades, listed starting with the north side and moving clockwise: the Mall Terrace Entrance façade, the River Terrace Entrance façade, the Concourse Entrance (or Metro Station) façade, the South Parking Entrance façade, and the Heliport façade.[28] On the north side of the building, the Mall Entrance, which also features a portico, leads out to a 600 ft (180 m) long terrace that is used for ceremonies. The River Entrance, which features a portico projecting out 20 ft (6.1 m), is located on the northeast side, overlooking the lagoon and facing Washington. There is a stepped terrace on the River Entrance that leads down to the lagoon, and a landing dock which was used until the late 1960s to ferry personnel between the Bolling Air Force Base and the Pentagon.[35] The main entrance for visitors is located on the southeast side, where the Pentagon Metro station and the bus station are located. There is also a concourse on the southeast side of the second floor of the building, which contains a mini-shopping mall. The Pentagon's south parking lot is located on the southwest side of the Pentagon, and the west side of the Pentagon faces Washington Boulevard. [36] The concentric rings are designated from the center out as "A" through "E" (with in addition "F" and "G" in the basement). "E" Ring offices are the only ones with outside views and are generally occupied by senior officials. Office numbers go clockwise around each of the rings, and have two parts: a nearest-corridor number (1 to 10) followed by a bay number (00 to 99), so office numbers range from 100 to 1099. These corridors radiate out from the central courtyard, with corridor 1 beginning with the Concourse's south end. Each numbered radial corridor intersects with the corresponding numbered group of offices (for example, corridor 5 divides the 500 series office block). There are a number of historical displays in the building, particularly in the "A" and "E" rings.

Floors in The Pentagon are lettered "B" for Basement and "M" for Mezzanine, both of which are below ground level. The concourse is located on the second floor at the metro entrance. Above ground floors are numbered 1 to 5. Room numbers are given as the floor, concentric ring, and office number (which is in turn the nearest corridor number followed by the bay number). Thus, office 2B315 is on the second floor, B ring, and nearest to corridor 3 (between corridors 2 and 3). One way to get to this office would be to go to the second floor, get to the A (innermost) ring, go to and take corridor 3, and then turn left on ring B to get to bay 15.[37]

A person can walk between any two points in less than seven minutes.[38]

Just south of the Pentagon are Pentagon City and Crystal City, extensive shopping and high-density residential districts in Arlington. Arlington National Cemetery is to the north. The Washington Metro Pentagon station is also located at the Pentagon, on the Blue and Yellow Lines. The Pentagon is surrounded by the complex Pentagon road network.[39]

The United States Postal Service Wikipedia has assigned six ZIP Codes to The Pentagon, and they are designated as being in Washington, D.C., even though The Pentagon is actually located in Virginia.[40]

Template:Wide image


The Pentagon Force Protection Agency (PFPA) is a United States government agency comprising both sworn federal police officers, the United States Pentagon Police and civilian CBRN technicians, and non-sworn civilian anti-terrorism investigative and physical security personnel, and is responsible for the protection of the Pentagon. The Department of Defense created the PFPA after the September 11, 2001 attacks. The new agency absorbed the Defense Protective Service (DPS) and assumed its role of providing basic law enforcement and security for the Pentagon and Department of Defense sites in the 280 acre (1.1 km²) "Pentagon Reservation" and greater National Capital Region (NCR). PFPA was also charged with providing force protection against the full spectrum of potential threats through robust prevention, preparedness, detection, and response measures. The United States Pentagon Police is the primary federal law enforcement arm of the Pentagon Force Protection Agency.


  1. Steve Vogel, The Pentagon: a History (2003).
  2. "The Pentagon – George Bergstrom – Great Buildings Online". Retrieved 2008-10-26. 
  3. 3.0 3.1 3.2 The Pentagon, Facts & Figures (accessed January 19, 2008)
  4. – Pentagon Memorial Dedication (accessed May 27, 2009)
  5. Vogel (2007), pp. 35–37
  6. Bureau of Public Roads memorandum, October 25, 1960.
  7. "General Information". Retrieved December 4, 2005. 
  8. Vogel, Steve (May 27, 2007). "How the Pentagon Got Its Shape". Washington Post. pp. W16. Retrieved 2007-05-26. 
  9. Roig-Franzia, Manuel (May 13, 2010). "Hemp fans look toward Lyster Dewey's past, and the Pentagon, for higher ground". The Washington Post. Retrieved May 25, 2010. 
  10. Goldberg (1992), p. 22
  11. 11.0 11.1 Goldberg (1992), p. 33
  12. Goldberg (1992), p. 29
  13. 13.0 13.1 Goldberg (1992), p. 34
  14. Vogel (2007), p. 131
  15. Goldberg (1992), p. 35; p. 44
  16. McGrath, Amanda (May 26, 2007). "How The Pentagon Got Its Shape (Gallery)". The Washington Post. 
  17. Goldberg (1992), p. 52–53
  18. Owens, Jim (February 2005). "Replacing the stone and rebuilding the Pentagon". Mining Engineering 57(2): 21–26. 
  19. Goldberg (1992), p. 39–42
  20. Goldberg, p. 36
  21. Goldberg (1992), p. 47; p. 52
  23. Renovation of the Pentagon. Retrieved October 7, 2006.
  24. "Flight 77, Video 2". Judicial Watch. 
  25. Isikoff, Michael; Daniel Klaidman (June 10, 2002). "The Hijackers We Let Escape". Newsweek. Retrieved Oct. 22, 2009. 
  26. 26.0 26.1 Schrader, Esther (September 16, 2001). "Pentagon, a Vulnerable Building, Was Hit in Least Vulnerable Spot". Los Angeles Times. Retrieved Feb. 25, 2010. 
  27. "Pentagon Renovation: Renovation Program Had Hardened the Facade Attacked on 9/11/01". 9-11 Research. Retrieved 2010-02-25. 
  28. 28.0 28.1 "The Pentagon". Retrieved 2010-02-25. 
  29. "Pentagon Renovation Program". Retrieved December 4, 2005. 
  30. "Americas: Pentagon staff reclaim destroyed offices". BBC News. August 15, 2002. Retrieved December 4, 2005. 
  31. "Pentagon History – September 11, 2001". Retrieved 2008-10-26. 
  32. Pentagon Memorial Web site
  33. Official press release at the United States Department of Defense
  34. Wilgoren, Debbie; Nick Miroff, Robin Shulman (2008-09-11). ""Pentagon Memorial Dedicated on 7th Anniversary of Attacks"". The Washington Post (The Washington Post Company). Retrieved 2008-09-11. 
  35. 35.0 35.1 Goldberg (1992), p. 57
  36. Vogel, Steve, "The Building That Runs Rings Around The Wiliest Generals", Washington Post, February 18, 2009, p. 11.
  37. "How to Find a Room in the Pentagon". Headquarters, Dept. of the Army. Retrieved September 13, 2007. 
  38. "Man shoots 2 officers outside Pentagon -". CNN. Retrieved May 25, 2010. 
  39. "Mixing Bowl Interchange Complex". Retrieved 2006-11-22. 
  40. Facts & Figures: Zip Codes


  • Goldberg, Alfred (1992). The Pentagon: The First Fifty Years. Office of the Secretary of Defense / Government Printing Office. 
  • Vogel, Steve (2007). The Pentagon – A History: The Untold Story of the Wartime Race to Build the Pentagon and to Restore it Sixty Years Later. Random House. 
  • Carroll, James (2007). House of War: The Pentagon and the Disastrous Rise of American Power. Mariner Books. 

External linksEdit


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