Headquarters of the Department of Defense, the Pentagon is one of the world's largest office buildings. It is twice the size of the Merchandise Mart in Chicago and has three times the floor space of the Empire State Building in New York. The Pentagon is virtually a city in itself. Approximately 26,000 employees, both military and civilian, contribute to the planning and execution of the defense of the USA.
While the Pentagon is not open to the public, it does offer tours to visitors with reservations. The facility hosts 106,000 visitors annually for reservation-only tours, which includes the mission of the Department of Defense and each of its branches of service, and visits numerous displays that highlight and depict significant moments in military history.
Tours are available Monday through Thursday from 10:00 A.M. to 4:00 P.M. and Friday from 12:00 P.M. to 4:00 P.M., and normally last approximately 60 minutes. Reservations may be booked from 14 to 90 days in advance. Learn more about tour guidelines here.
You can also visit the National 9/11 Pentagon Memorial, while onsite.