Pentagon is the world’s largest office building. The majority of large building lists are based on height. By that metric, the Burj Khalifa in Dubai is the tallest at 2,717 feet. One Globe Trade Center, which is 1,776 feet tall and ranks sixth in the world, is the largest American skyscraper on the list.

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Bird’s eye view of The Pentagon _©

Another method of measuring is the square footage of a building’s floor space. By that metric, the Pentagon, America’s military headquarters since 1943, is by far the greatest structure. At the same time, you may go from one end to the other in about 7 minutes. The Pentagon is the world’s biggest office building controlled by a single entity, and it ranks 14th on the list of the world’s largest structures.

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Size and Scale facts of The Pentagon _©

The structure, designed by American architect George Bergstrom and constructed between 1941 and 1943, serves as the headquarters of the United States Department of Defense, which includes all three military services—Army, Navy, and Air Force. With 703,000 civilian employees, the department is the largest in the United States.

The Pentagon was built on the location of Lower Hell, a slum where African Americans were the major residents. The pentagonal form of the structure was influenced by the peculiarities of the surrounding landscape. It was originally intended to be built at the intersection of numerous highways at an angle of 108 degrees (pentagon angle). The project was authorized, but the president eventually decided that it would impede the view of Washington. The structure was relocated downstream of the Potomac River, but the form was not altered.

The Pentagon earned its name from the fact that it has five sides and is seven floors tall. There are 131 stairwells and 19 escalators. The Pentagon’s five sides are 281 meters long, while the perimeter is 1405 meters long. The overall length of the corridors is 28 kilometers, and the total floor surface is more than 600,000 m2, which is three times the size of the Empire State Building in New York.

The pentagonal design allows you to reach the most remote part of the structure in about 7 minutes. Another fascinating fact: the Pentagon has twice as many bathrooms as are required for the number of people working there. This is not a strategic maneuver, but rather a historical architectural aspect.

When segregation was the law in Virginia, the Pentagon was built. However, Roosevelt had signed an executive order the previous year prohibiting discrimination against government employees based on race, creed, color, or national origin. As a result, the Pentagon became Virginia’s only non-segregated building. Because segregation was required by state law, the Pentagon had twice as many bathrooms as a desegregated structure of its size.

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Construction and costs of The Pentagon _©

During construction, the builders saved enough steel to build a battleship. The 689,000 tonnes of sand and gravel required to produce the reinforced concrete on the structure, including 41,000 concrete pilings, came from the adjacent Potomac River.

More than 15,000 laborers worked around the clock, and due to wartime office space shortages, workers moved in before the Pentagon was completed. Construction was completed on January 15, 1943, about 16 months after it began. However, speed comes with a cost: The original budget was $35 million, but the ultimate cost was $63 million, which is more than $900 million in today’s money.

The construction comprises five levels, omitting the mezzanine and basement, and is made of steel and reinforced concrete with some limestone face. It is made up of five concentric pentagons, or “rings,” connected by ten spoke-like passageways. Several libraries operate as military research institutions, and these repositories subscribe to almost 1,700 journals in a wide range of languages. There are also two cafeterias, a dining room, and seven snack bars on the property. There are 67 acres (27 hectares) of parking lots, which can accommodate around 8,700 cars. The bus and taxi terminals are built beneath a massive concourse that also houses a retail center for Pentagon personnel. The facility is also served by the Washington Metro subway, and a heliport was established in 1956.

“A lot of attention has gone into defending the Pentagon from fire. It is a fire-resistant structure due to its steel-reinforced concrete construction. The major internal walls above the basement level are also made of masonry. Reinforced concrete firewalls with double, automated fire doors split the basement, which houses the maintenance shops, garage, and storage rooms, into fire zones. Masonry walls and fire doors safeguard transformer vaults and machine rooms throughout the structure.

September 11 attacks | Pentagon

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A glimpse of The Pentagon during the 9/11 Attack _©

During the September 11 attacks, five terrorists hijacked a commercial airplane and flew it into the Pentagon on the 60th anniversary of its construction. Part of the southwest side of the building was demolished, killing the hijackers and 184 civilians caught between the jet and the structure. Within a year, the majority of the damage was rectified.


  1. B. Philip Bigler (2019). Pentagon | History & Features. In: Encyclopædia Britannica. [online] Available at:
  2. ForumDaily. (2022). Pentagon: riddles of the world’s largest office building. [online] Available at: [Accessed 2 Feb. 2023].
  3. U.S. Department of Defense. (n.d.). 10 Things You Probably Didn’t Know About the Pentagon. [online] Available at:
  4. GreatBuildings. (n.d.). The Pentagon by George Bergstrom at GreatBuildings. [online] Available at: [Accessed 2 Feb. 2023].
  5. Anon, (n.d.). This Is the Largest Office Building in the World – 24/7 Wall St. [online] Available at: [Accessed 2 Feb. 2023].



Prerana is upbeat, strong willed and fiercely moral. She is an aspirant in the architecture field with a keen interest in researching and understanding parallels between human behaviour and architecture. She believes in breaking stereotypes whether in architecture or life. Prerana's enthusiasm and optimism fuels her every move. When alone, one can find her with the animals and capturing stories through her lens.