To take a guided tour of the Pentagon, you must make a reservation using the Pentagon Tour Reservation Portal. Each adult member of your tour group must then register as a Pentagon Visitor and be cleared by the Pentagon Force Protection Agency to visit the Pentagon for your tour. Tours can fill up quickly, so booking your tour well before your visit is advisable. Reservations may be booked from 14 to 90 days in advance.
More information about Pentagon tours may be found on the Pentagon Tours Webpage.