11 Sep 1941: Pentagon groundbreaking

On this day in 1941, ground was broken on The Pentagon, the new headquarters of the Department of War, in Alexandria, Virginia.

Exactly 60 years later, hijackers flew American Airlines Flight 77 into the building as part of the 9/11 attacks.

When Germany broke its truce and invaded the Soviet Union in May 1941, the Department of War had 24,000 employees in 17 buildings. The department already had a new building in the works at Foggy Bottom, in D.C. proper; it would be too small. (It’s now the home of the Department of State.)

The solution was to build one of the world’s largest office buildings across the Potomac River. Its 17.5 miles of corridors connect its 6.5 million square-foot area. As steel would be needed in the event the U.S. joined WWII, the building had to be spread out over a large area, as opposed to a traditional office tower.

The building was initially planned for a pentagonal site in Arlington, Virginia; the current site was chosen due to concerns that the building would block the view of Arlington National Cemetery from Washington. Planners kept the shape, however.

The interior courtyard covers five acres; until 9/11, it was known as “ground zero” because of the assumption that it would be a primary Soviet nuclear target.

Image: Pentagon viewed from the northeast, 2008. David B. Gleason.