Pentagon Building is one of the largest office buildings in the world. It houses the headquarters of the Department of Defense of the United States government. The building lies on the west bank of the Potomac River in Arlington, Virginia, across from Washington, D.C.
Built in the form of a pentagon, or five-sided figure, the building has five concentric rings connected by 10 spokelike corridors. It has five floors, a mezzanine, and a basement. The building covers 29 acres (12 hectares) and has about 3,706,000 square feet (344,300 square meters) of office and other space. The outermost wall of the concrete structure is faced with Indiana limestone. The building is surrounded by 200 acres (81 hectares) of lawn and terraces. Adjacent parking areas cover 67 acres (27 hectares) and can hold about 10,000 vehicles. The lagoon at the building’s river entrance was formed by excavation and juncture with the river.
About 23,000 people work in the building. Most of them work for the departments of the Army, Navy, or Air Force, or the Office of the Secretary of Defense. About half of them are civilians.
The Pentagon Building has one of the world’s largest private telephone systems and the largest pneumatic tube system. Pneumatic tubes transport letters and other such materials by means of air pressure. The building also has many shops, several cafeterias and restaurants, a radio and television station, a bank, a medical dispensary, a post office, and a heliport.
Army engineers began building the Pentagon in September 1941 and completed it by January 1943. It was built to house the scattered offices of the War Department under one roof. The building cost $83 million.
On Sept. 11, 2001, the Pentagon Building was damaged in the worst terrorist attack in U.S. history. Terrorists in a hijacked commercial jetliner deliberately crashed into the Pentagon, cutting a gash in one side of the building and setting it on fire. Two other planes crashed into the two towers of the World Trade Center in New York City. A fourth hijacked plane crashed in Pennsylvania. Thousands of people died as a result of the attacks. A memorial to the victims of the Pentagon attack was dedicated on Sept. 11, 2008. See also September 11 terrorist attacks .
