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Sept. 11: Construction of Pentagon began in 1941

Jennifer Karmon

In 1941 -- 60 years to the day before the worst terrorist attack on American soil occurred on 9/11 -- ground was broken on the Pentagon. In tribute to that proud American symbol, Yahoo Homes is taking a look at the architecture of the Pentagon.

Specifically, why in the world is it shaped like a pentagon?

The short answer: It was a bit of an accident.

According to a long (and worth every word) 2007 story in the Washington Post called "How the Pentagon Got Its Shape," the World War II effort dictated a couple of factors:

  • The building -- the world's biggest office building -- needed to house as many as 40,000 workers.
  • It couldn't be more than four stories tall, because that would require too much steel (needed for the war effort) and would obstruct views of D.C.
  • It needed to be built fast -- six months from design to the first move-in phase, plus another six months for absolute completion.

The group working on the Pentagon had been a single weekend to come up with a basic design. Members quickly settled on a site in Arlington, Va. (not least because a powerful Virginia congressman would appreciate it). The tract was oddly shaped, bounded on five sides. But the interior distances of a square or a rectangle would be too vast.

An irregular pentagon would have to do, according to the Post story.


The story doesn't end there.

The site was one of D.C.'s most prominent, and the "frankly ugly" building was in view of the tomb of D.C.'s revered designer, Pierre L'Enfant. The protectors of the capital's beauty and integrity could not let that stand.

A new site was chosen. The Post writes:

"The original rationale for Bergstrom's pentagonal design was gone. The building no longer would be constructed on the five-sided Arlington Farm site. Yet the chief architect and his team continued with plans for a pentagon at the new location. There was no time to change them.

"Besides," the Post continues, "the pentagon design still worked.

" Like a circle, a pentagon would create shorter walking distances within the building -- 30 to 50 percent less than in a rectangle, architects calculated -- but its lines and walls would be straight and, therefore, much easier to build. The move from the odd-shaped Arlington Farm site freed the architects from the need to make the building asymmetrical. The advantages gained -- a smoother pedestrian flow, better space arrangement, and easier distribution of utilities around the building -- 'proved startling,' the architects concluded."

And then President Franklin D. Roosevelt sealed the deal: "I like it because nothing like it has ever been done that way before."

Today, the Pentagon has more than 17 miles of corridors, yet "movement between any two opposite points takes as little as seven minutes," according to the official Pentagon website. At its peak, the building has held 33,000 workers; currently, about 23,000 work there. It has triple the floor space of the Empire State Building, and the U.S. Capitol could fit into any of its five sides.