President Barack Obama and First Lady Michelle Obama, former President George W. Bush and former First Lady Laura Bush at the North Pool Memorial

President Barack Obama and First Lady Michelle Obama, along with former President George W. Bush and former First Lady Laura Bush look at the North Pool Memorial prior to a commemoration ceremony on the tenth anniversary of the 9/11 attacks against the United States, at the National September 11 Memorial, World Trade Center site, New York, N.Y., Sunday, Sept. 11, 2011.