The Pentagon spans a gross area of about 6.34 million square feet (about 34 acres). This building includes five floors plus a basement and a partial mezzanine, reaching a total height of about 71 feet. WIthin the halls of the Pentagon are five concentric pentagonal rings, intersected by ten corridors for a total walking distance of about 17.5 miles. Despite the Pentagon's massive size, the average time to walk between two points is only about seven minutes.
In the center of the Pentagon is the five acre area known as the Center Courtyard. Due to their location on the internal portion of the Pentagon, the B, C, and D Rings have flat built roofs, while the A-Ring (facing the Center Courtyard) and the E Ring (facing externally) both have sloping slate roofs. The total roof area amasses about 29 acres of space. The building is also compromised of 7,754 external windows with a surface area of 309,276 square feet. This internal building space is used daily for offices, concessions, communal, and storage requirements of the Pentagon's 25,650 employees.