U.S. President Barack Obama, first lady Michelle Obama and former president George W. Bush walk past the North Pool at the National September 11 Memorial during tenth anniversary ceremonies at the World Trade Center site in New York

Reuters

Reuters

U.S. President Barack Obama, first lady Michelle Obama and former president George W. Bush walk past the North Pool at the National September 11 Memorial during tenth anniversary ceremonies at the World Trade Center site in New York, September 11, 2011. The 9/11 attacks changed life in the United States forever, but 10 years after the devastating hit, New Yorkers have learned to live in a more dangerous world and are ready to move on. REUTERS/Justin Lane/Pool (UNITED STATES)