Construction on the Pentagon was completed in January 1943. With about 6.4 million square feet, it is still today the world’s largest low-rise office building. Wikimedia Commons/ Master Sgt. Ken Hammond, U.S. Air Force
The Pentagon is not only a symbol of America's military might but also one of the most iconic buildings in the world. However, what sets it apart is its unique pentagonal shape. So how did it come to be that way?
A Unique Solution to a Growing Problem
In 1941, as America was preparing for war and the federal workforce in Washington, D.C. was expanding, the War Department needed a new headquarters. Spread out across 17 buildings in the city, the 24,000 employees required more permanent office space. Brig. Gen. Brehon Burke Somervell, head of the Army's Construction Division, was tasked with finding a solution.
Under the guidance of Lt. Col. Hugh J. Casey, the chief of the design section, architects and designers came up with a creative pentagonal plan that maximized the odd dimensions of the five-sided parcel of land below Arlington National Cemetery. The building would have several concentric rings of office space linked through corridors, with a central courtyard.
On September 11, 2001, American Airlines Flight 77 slammed into the building, killing 184 people—64 on the plane, including five hijackers—and 120 Pentagon employees. Wikimedia Commons/Cpl. Jason Ingersool, USMC
Overcoming Controversy and Challenges
Although the design was met with resistance from conservationists who feared it would obstruct the scenic views of Washington, President Franklin D. Roosevelt approved the unique shape of the building for its originality. However, the location of the Pentagon was changed to its current site at the foot of the Virginia side of the 14th Street bridge over the Potomac River.
The new plot of land allowed for more flexibility in design, but the architects stuck with the pentagonal plan due to its many advantages. It offered easier access between different parts of the building compared to a conventional layout. The structure also had to be no more than four stories high to maintain unobstructed views of the city across the Potomac River.
So as not to obstruct views of the city across the Potomac River, the structure is no more than four stories high. Library of Congress, Carol M. Highsmith
A Building to Withstand the Test of Time
The Pentagon's pentagonal shape met the requirements set by General Somervell, including providing office space for 40,000 people and minimizing the use of steel during construction due to its scarcity. Despite criticism from the U.S. Commission of Fine Arts, the building's unique design was favored by President Roosevelt.
After 17 months of construction, the Pentagon was completed in January 1943. With approximately 6.4 million square feet, it remains the world's largest low-rise office building to this day. Over time, the Pentagon has undergone renovations to meet modern standards and accommodate changes in the workforce.
An aerial view of the Pentagon, 2002 Wikimedia Commons, USGS
Beyond the Shape: A Legacy of Adaptation
While the Pentagon never housed the entire U.S. Defense Department as originally intended, it has continuously adapted to the changing needs of the military. A massive renovation completed in 2011 posed new challenges, as modern offices and cubicles required more space than the open bays where lower-level personnel used to work. The renovation also addressed issues such as outdated electrical systems and insufficient fire safety measures.
Despite its somber history, including the tragic events of September 11, 2001, the Pentagon remains a symbol of resilience. It continues to serve as a crucial hub for the U.S. military, accommodating thousands of dedicated workers who navigate its extensive corridors daily.
So as not to obstruct views of the city across the Potomac River, the structure is no more than four stories high. Library of Congress, Carol M. Highsmith
It's Your Turn to Ask Smithsonian
The Pentagon's distinct shape has captivated the world for decades. Now that you know the story behind its construction, what other questions do you have for us? Ask Smithsonian and satisfy your curiosity about the wonders of our world.
