The Pentagon was dedicated on January 15, 1943 and it is the world's largest office building. Those who work within its walls often simply call it "the Building" or "Fort Fumble." The term "the Pentagon" is often used to refer to the Department of Defense, rather than the building itself. The building, located in Arlington County, Virginia is pentagon-shaped in plan and houses approximately 23,000 military and civilian employees and about 3,000 non-defense support personnel, making it the highest-capacity low-rise office building in the world. It has five floors above ground (and two basement levels) and each floor has five ring corridors. Its unusual shape results from the fact that its originally intended site, Arlington Farms, was surrounded by five roads. Franklin D. Roosevelt had it moved to its current location because he didn't want the new building to obstruct the view of Washington D.C. from Arlington Cemetery.
The United States Department of Defense, abbreviated as DoD or DOD and sometimes called the Defense Department, is a civilian Cabinet organization of the United States government. The Department of Defense controls the U. S. military and is headquartered at The Pentagon. It is headed by the Secretary of Defense,
The Department of Defense is based in The Pentagon in Arlington County, Virginia outside Washington, DC, across the Potomac River. It was created by combining the War Department (founded in 1789) with the Navy Department (founded in 1798; formerly the Board of Admiralty, founded in 1780), and the newly created Department of the Air Force. The department was formed in order to reduce inter service rivalry which was believed to have reduced military effectiveness during World War II.