pentagon 3

The United States Department of War was headquartered in the Greggory Building, a temporary structure erected during World War I along Constitution Avenue on the National Mall. The War Department, which was a civilian agency created to administer the U.S. Army, was spread out in additional temporary buildings on National Mall, as well as dozens of other buildings in Washington, D.C., Maryland and Virginia. In the late 1930s a new War Department Building was constructed at 21st and C Streets in Foggy Bottom but, upon completion, the new building did not solve the department's space problem and ended up being used by the Department of State.^[6] When World War II broke out in Europe, the War Department rapidly expanded with anticipation of being drawn into the conflict. Secretary of War Henry L. Stimson found the situation unacceptable, with the Munitions Building overcrowded and the department spread out.^[7][8]
Stimson told President Franklin D. Roosevelt in May 1941 that the War Department needed additional space. On July 17, 1941, a congressional hearing took place, organized by Virginia congressman Clifton Woodrum, regarding proposals for new War Department buildings. Woodrum pressed Brigadier General Eugene Reybold, who was representing the War Department at the hearing, for an "overall solution" to the department's "space problem" rather than building yet more temporary buildings. Reybold agreed to report back to the congressman within five days. The War Department called upon its construction chief, General Brehon Somervell, to come up with a plan.^[9]

Main Navy Building (foreground) and the Munitions Building were temporary structures built during World War I on the National Mall. The Munitions Building served as the Department of War headquarters for several years before moving into the Pentagon.

Southwest view of the Pentagon with the Potomac River and Washington Monument in background (1998)

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 the Department of Agriculture's Arlington Experimental Farm, adjacent to Arlington National Cemetery, and the obsolete Washington Hoover Airport site.^[10]
The site originally chosen was Arlington Farms which had a roughly pentagonal shape, so the building was planned accordingly as an irregular pentagon.^[11] Concerned that the new building could obstruct the view of Washington, D.C. from Arlington Cemetery, President Roosevelt ended up selecting the Hoover Airport site instead.^[12] The building retained its pentagonal layout because a major redesign at that stage would have been costly, and Roosevelt liked the design. Freed of the constraints of the asymmetric Arlington Farms site, it was modified into a regular pentagon.^[13][14]