Vice President Joe Biden places a wreath at the Pentagon Memorial, May 5, 2011, in honor of the 184 who were killed there on Sept. 11, 2001. Defense Secretary Robert M. Gates and Marine Corps Gen. James E. Cartwright, vice chairman of the Joint Chiefs of Staff, look on along with Arlington County, Va., firefighters who were among the first responders to the disaster. The ceremony took place four days after 9/11 mastermind Osama bin Laden, al-Qaida's leader, was killed during a U.S. military raid in Pakistan. Vice President Joe Biden places a wreath at the Pentagon Memorial, May 5, 2011, in honor of the 184 who were killed there on Sept. 11, 2001. Defense Secretary Robert M. Gates and Marine Corps Gen. James E. Cartwright, vice chairman of the Joint Chiefs of Staff, look on along with Arlington County, Va., firefighters who were among the first responders to the disaster. The ceremony took place four days after 9/11 mastermind Osama bin Laden, al-Qaida's leader, was killed during a U.S. military raid in Pakistan. SHARE: Download: Full Size (1.34 MB) Tags: Photo Essays Credit: VIRIN: 065636-O-KHV21-391.jpg Photo Gallery