President Barack Obama Greets Guest At The National September 11 Memorial

President Barack Obama and First Lady Michelle Obama, along with former President George W. Bush and former First Lady Laura Bush, greet family members and local dignitaries at the National September 11 Memorial in New York, N.Y., on the tenth anniversary of the 9/11 attacks against the United States, Sunday, Sept. 11, 2011. (Official White House Photo by Pete Souza)