In 1941, when the likelihood of America’s entrance in World War II increased, leading U.S. politicians began seriously to worry about their War Department, whose various sections were spread over several buildings and across two states (Maryland and Virginia), making any departmental cooperation time-consuming and difficult. In July that year, Brig. General Brehon Somervell, head of the Army’s Construction Department and charged with the task to find a solution, began looking for an area outside Washington D.C. that was large enough for his idea of the future headquarters of what would become the United States Department of Defense: a building that could hold up to 40,000 people with an adjacent parking area for about 10,000 cars. The space available on the initially chosen site bordering Arlington National Cemetery (Virginia) determined the pentagonal design (by architects George E. Bergstrom and David J. Witmer). This shape was maintained and perfected even though the construction site was slightly shifted. Ground was broken on September 11, 1941, and within about 16 months the five-floor Pentagon was completed, covering an area of about 600,000 m2, of which 340,000 m2 are for offices.
Those interested in some less known facts may enjoy reading Somervell’s Folly, or History in the Headlines. Stephen F. Vogel wrote The Pentagon: A History (2007), excerpts of which were published in the Washington Post (27 May 2007). Here are some History facts with audio-visual material, to be complemented by The Pentagon’s “Fact and Figures”.