Pentagon on 9/11 The plane that hit the Pentagon, Sept. 11, 2001, peeled the building's reinforced concrete back all the way to the "B" ring. The area outside the Pentagon became a staging area for medical and emergency personnel. SHARE IMAGE: Download Image: Full Size (1.3 MB) Photo By: Jim Garamone, DOD VIRIN: 010911-D-FN314-001M.JPG Photo Gallery