Home Page About Us

The Pentagon

The Pentagon, headquarters of the Department of Defense, is one of the world's largest office buildings. It is twice the size of the Merchandise Mart in Chicago, and has three times the floor space of the Empire State Building in New York. The National Capitol could fit into any one of the five wedge-shaped sections.

The Pentagon—a building, institution, and symbol—was conceived at the request of Brigadier General Brehon B. Sommervell, Chief of the Construction Division of the Office of the Quartermaster General, on a weekend in mid-July 1941. The purpose was to provide a temporary solution to the War Department's critical shortage of space. The groundbreaking ceremony took place on September 11, 1941. The building was dedicated on January 15, 1943, nearly 16 months to the day after the groundbreaking.

The original site chosen for the Pentagon was a tract of land known as Arlington Farms. The site was bordered by five roadways thus dictating the concept of a pentagonal shaped building. Fearing the enormous building would interfere with the view of Washington, D.C. from Arlington Cemetery, President Franklin Delano Roosevelt directed the building be moved three quarters of a mile down river. The new location chosen was at the site of the old Hoover Airport, a brick factory, a pickle factory, a race track, and a low-income residential area known as Hell’s Bottom. On this site, the final design concept of an open air court surrounded by five concentric pentagonal rings (or corridors) traversed by ten spoke-like corridors was constructed.

The architectural style of the Pentagon is Stripped Neo-Classical. The building was constructed out of reinforced concrete made from 380,000 tons of sand dredged from the Potomac River and supported by 41,492 concrete piles. The designers’ ingenuity not only created a building that reflected the architectural style of the nation’s Capitol but also saved enough steel to build one battleship. At the height of construction, over 1,000 architects worked in an adjacent hanger producing enough prints to supply the 14,000 construction workers and tradesmen. Three shifts worked 24 hours a day, every day, constructing the Pentagon wedge by wedge. These wedges were occupied as they came on-line. The building was dedicated on January 15, 1943, nearly 16 months to the day after the groundbreaking.


The Pentagon is virtually a city in itself. Approximately 23,000 employees, both military and civilian, contribute to the planning and execution of the defense of our country. These people arrive daily from Washington, D.C. and its suburbs over approximately 30 miles of access highways, including express bus lanes and one of the newest subway systems in our country. They ride past 200 acres of lawn to park approximately 8,770 cars in 16 parking lots; climb 131 stairways or ride 19 escalators to reach offices that occupy 3,705,793 square feet. While in the building, they tell time by 4,200 clocks, drink from 691 water fountains, utilize 284 rest rooms, consume 4,500 cups of coffee, 1,700 pints of milk and 6,800 soft drinks prepared or served by a restaurant staff of 230 persons and dispensed in 1 dining room, 2 cafeterias, 6 snack bars, and an outdoor snack bar. The restaurant service is a privately run civilian operation under contract to the Pentagon.

Over 200,000 telephone calls are made daily through phones connected by 100,000 miles of telephone cable. The Defense Post Office handles about 1,200,000 pieces of mail monthly. Various libraries support our personnel in research and completion of their work. The Army Library alone provides 300,000 publications and 1,700 periodicals in various languages.


Stripped of its occupants, furniture and various decorations, the building alone is an extraordinary structure. Built during the early years of World War II, it is still thought of as one of the most efficient office buildings in the world. Despite 17.5 miles of corridors it takes only seven minutes to walk between any two points in the building.

The original site was nothing more than wasteland, swamps and dumps. 5.5 million cubic yards of earth, and 41,492 concrete piles contributed to the foundation of the building. Additionally, 680,000 tons of sand and gravel, dredged from the nearby Potomac River, were processed into 435,000 cubic yards of concrete and molded into the Pentagon form. The building was constructed in the remarkably short time of 16 months and completed on January 15, 1943 at an approximate cost of $83 million. It consolidated 17 buildings of the War Department and returned its investment within seven years.

Total Land Area (acres) 583 
Government Owned (acres) 296 
Purchased or Condemned (acres) 287 
Total Land Cost $2,245,000 
Area Covered by Pentagon Building (acres) 29 (34 including courtyard) 
Area of Center Courtyard (acres) 5 
Area of Heating and Refrigeration Plant (acres) 1 
Area of Sewage Structures (acres) 1 
Access Highways Built (miles) 30 
Overpasses and Bridges Built 21 
Parking Space (acres) 67 
Capacity (vehicles) 8,770 
Cost of Building $49,600,000 
Total Cost of Project (including outside facilities) $83,000,000 
Gross Floor Area (sq. ft.) 6,636,360 
Net Space for Offices, Concessions and Storage (sq. ft.) 3,705,793 
Cubic Contents (cu. ft.) 77,015,000 
Length of Each Outer Wall (ft.) 921 
Height of Building (ft.) 77' 3.5" 
Number of Floors, plus Mezzanine and Basement 5 
Total Length of Corridors (miles) 17.5
Building Proposed mid-July 1941 
Prime Contract Awarded 11 August 1941 
Mechanical Engineering Contract Awarded 3 September 1941 
Construction Began 11 September 1941 
Grading Contract Awarded 24 September 1941 
First Occupants Move in 29 April 1942 
Construction Completed 15 January 1943 
Sand & Gravel Used for Concrete (tons) 680,000 
Buildings Consolidated to Populate the Pentagon 17 

Concept to Early Construction (1941-1942)

Original Sketch for the Pentagon Building, 21 July 1941 

Original Sketch for the Pentagon Building, 21 July 1941

By the summer of 1941, the War Department work force in the Washington, D.C. area numbered more than 24,000 civilian and military personnel housed in 17 buildings and was expected to reach 30,000 by the beginning of 1942. Providing office space for the workers was part of the military construction mission of the Quartermaster Corps’ Construction Division, already struggling to cope with the vast mobilization construction underway before the United States entered World War II.

The federal government considered constructing temporary buildings, but Brigadier General Brehon B. Somervell, an aggressive Engineer officer who headed the construction division, had another idea. On Thursday, 17 July 1941, he summoned two of his subordinates, Lieutenant Colonel Hugh J. Casey, also an Engineer officer, and George E. Bergstrom, a prominent civilian architect, and told them that by Monday morning he wanted basic plans and an architectural perspective for an air-conditioned office building to house 40,000 workers in four million square feet of space, not more than four stories high, with no elevators. Indeed, Lieutenant Colonel Casey and his staff completed the basic layout of a five-sided building by that following Monday, after what he later described was "a very busy weekend."

Brigadier General Brehon B. Somervell 

Brigadier General Brehon B. Somervell

Lieutenant Colonel Hugh J. Casey 

Lieutenant Colonel Hugh J. Casey

The War Department staff approved the building’s basic concept that Monday and the Secretary of War approved it on Tuesday, informing President Franklin D. Roosevelt of his plans. Also on Tuesday Somervell took the plan to Congress. Sensitive to the severity of the space problem, Congress and the president moved quickly to approve a supplemental defense appropriation bill, including $35 million for the construction of the proposed War Department headquarters.

The plans underwent many changes in the next few months, including changes in location. With Somervell’s approval, Casey and Bergstrom sited the building between Arlington National Cemetery and Memorial Bridge. Some federal agencies and local citizens did not want the proposed building to obstruct the vista between the Lincoln Memorial and Arlington Cemetery. Appeasing opponents, in August President Roosevelt moved the site to its current location.

Early sketch of pentagonal design at Arlington Farms site 

Early sketch of pentagonal design at Arlington Farms site

Plans for the building proceeded swiftly. Bergstrom with architect David J. Witmer developed plans for a unique reinforced concrete building that would consist of five concentric pentagons separated by light wells and connected by radiating spoke-like corridors. It would have five stories and include a six-acre interior court, numerous ramps and escalators, a large shopping concourse on the first floor, taxi stands and bus lanes, and parking for 8,000 cars.

Construction to Completion (1943)

Northwest exposure of the Pentagon's construction, 1 July 1942. 

Northwest exposure of the Pentagon's construction, 1 July 1942

Construction commenced on 11 September 1941, and continued rapidly during the winter of 1941-42. Architects for the project had little or no lead time; sometimes construction actually outpaced planning. On 1 December 1941, when the president signed legislation transferring the military construction mission from the Quartermaster Corps to the Army Corps of Engineers, 4,000 men were laboring on the building in three shifts. One section was completed by the end of April 1942 and the first tenants moved in. The basic shell and roof were finished in one year, and the building was completed by 15 January 1943.

The Pentagon's facade nearing completion. 

The Pentagon's facade nearing completion

The Pentagon’s designers minimized or avoided using critical war materials whenever possible. They substituted concrete ramps for passenger elevators and used concrete drainpipes rather than metal. They eliminated bronze doors, copper ornaments, and metal toilet partitions, and avoided any unnecessary ornamentation.

The Pentagon was the largest office building in the country at that time covering 29 acres and housing 17.5 miles of corridors. Design and construction of such a building would normally have taken four years, but the Corps took only 16 months. At its peak the Pentagon housed nearly 33,000 workers.

Aerial view of the Pentagon under construction. 

Aerial view of the first two Pentagon "spokes" under construction

The architects and Engineer officers who designed and constructed the Pentagon produced one of the most innovative and unique structures of the war era. With this massive yet efficient structure, the Corps not only resolved the problem of housing thousands of War Department employees during the war years, they also provided for future War Department needs.

September 11, 2001

"Freedom itself was attacked this morning by a faceless coward and freedom will be defended... make no mistake, we will show the world that we will pass this test." George W. Bush

Firefighters struggle to contain the fire, September 11, 2001 

Firefighters struggle to contain the fire, September 11, 2001

Exactly 60 years to the day after the groundbreaking ceremony, the September 11, 2001 attacks occurred. American Airlines Flight 77 crashed into the west side of the Pentagon after being hijacked, killing all aboard as well as over a hundred people within the Pentagon. The flight penetrated three of the five rings of the Pentagon. Because the affected area was under renovation at the time, several offices were unoccupied, sparing many lives. The aircraft struck on the edge between two sections—one of which had just finished being upgraded.

Contractors involved in the Pentagon Renovation Program were also charged with the task of rebuilding the damaged section of the Pentagon following the attacks. This additional project was named the "Phoenix Project", with the goal of having the outermost offices in the damaged section occupied again by September 11, 2002. Part of the pre-attack renovation had involved adding improved security features, including walls and windows with greater blast resistance. An initial analysis suggested that the section's improvements had saved lives, enabling more people to evacuate.


Aftermath from a terrorist attack of the Pentagon, September 11, 2001

Repairs included demolition of the damaged areas, complete rebuilding of the area that had previously been renovated, and reconstruction of the shell of the unrenovated section. The first Pentagon tenants whose offices were damaged in the attack began moving back in on August 15, 2002, nearly a month ahead of schedule. The repairs cost the Department of Defense about $500,000,000. Before the September 11, 2001 attacks, an escalator ran from the Metro station to the Pentagon lobby. After the attack this escalator was blocked off and later removed as part of the Pentagon Renovation Program.

Credit: United States Department Of Defense