President Barack Obama and First Lady Michelle Obama, along with former President George W. Bush and former First Lady Laura Bush, pause at the North Memorial Pool of 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. The North Memorial pool sits in the footprint of the north tower, formerly 1 World Trade Center. (Official White House Photo by Chuck Kennedy)