U.S President George W. Bush, former U.S. Secretary of Defense Donald Rumsfield (R), current U.S. Secretary of Defense Robert Gates (2nd L) observe the first inscribed memorial unit being unveiled at the Pentagon Memorial September 11, 2008. The national memorial is the first to be dedicated to those killed at the Pentagon on September 11, 2001. The site contains 184 inscribed memorial units honoring the 59 people aboard American Airlines Flight 77 and the 125 in the building who lost their lives that day. REUTERS/Cherie Cullen-US Department of Defense/Pool (UNITED STATES)