New York, Ground Zero: On Sunday morning, to mark the tenth anniversary of 9/11 at the World Trade Center, President Obama and First Lady Obama walk with former President George W. Bush and Mrs. Laura Bush by one of the reflecting pools that is a memorial to the victims of 9/11, built in the footprint of the Twin Towers.

The names of the dead are etched into the stone surrounding the two pools, and the foursome ran their hands over the names before joining thousands of families for a memorial ceremony.
*AP photos