<human>:  I have a question about the Department of Defense. Where is the Pentagon?
<bot>: The Pentagon is located in Arlington, Virginia. It is the headquarters of the Department of Defense. The Pentagon is a large complex of buildings that includes the headquarters of the Joint Chiefs of Staff, the Office of the Secretary of Defense, the Office of the Secretary of the Army, the Office of the Secretary of the Air Force, and the Office of the Secretary of the Navy.