South of Arlington Cemetery is the Pentagon, the largest office building in the world. Outside you may visit the Pentagon Memorial ; 184 illuminated benches honor each person killed in the September 11, 2001, terrorist attack on the Pentagon. To get inside the building, you'll have to book a free guided tour on the website. Make reservations 14 to 90 days in advance.
Nearby, the Pentagon, you can spot three soaring arcs of the Air Force Memorial , which invokes the contrails of jets.
