<P> The Pentagon is the world 's largest office building , with about 6,500,000 sq ft ( 600,000 m ) , of which 3,700,000 sq ft ( 340,000 m ) are used as offices . Approximately 23,000 military and civilian employees and about 3,000 non-defense support personnel work in the Pentagon . It has five sides , five floors above ground , two basement levels , and five ring corridors per floor with a total of 17.5 mi ( 28.2 km ) of corridors . The Pentagon includes a five - acre ( 20,000 m ) central plaza , which is shaped like a pentagon and informally known as `` ground zero , '' a nickname originating during the Cold War on the presumption that it would be targeted by the Soviet Union at the outbreak of nuclear war . </P>
<P> The Pentagon is the world 's largest office building , with about 6,500,000 sq ft ( 600,000 m ) , of which 3,700,000 sq ft ( 340,000 m ) are used as offices . Approximately 23,000 military and civilian employees and about 3,000 non-defense support personnel work in the Pentagon . It has five sides , five floors above ground , two basement levels , and five ring corridors per floor with a total of 17.5 mi ( 28.2 km ) of corridors . The Pentagon includes a five - acre ( 20,000 m ) central plaza , which is shaped like a pentagon and informally known as `` ground zero , '' a nickname originating during the Cold War on the presumption that it would be targeted by the Soviet Union at the outbreak of nuclear war . </P>
what 's at the center of the pentagon
what 's at the center of the pentagon
a five - acre ( 20,000 m ) central plaza
a five - acre ( 20,000 m ) central plaza