Republican presidential candidates Donald Trump, left speaks at a Republican presidential debate last month, as former Florida Gov. Jeb Bush listens. Mark J. Terrill/AP hide caption
9/11
An artist's image of the wall that will separate the public from the repository where unidentified remains will be kept at the National September 11 Memorial Museum in Manhattan. 911memorial.org hide caption
A woman looks out at One World Trade Center from inside the 9/11 Empty Sky memorial at Liberty State Park in Jersey City, N.J., on Wednesday. Americans commemorated the 12th anniversary of the Sept. 11 attacks with solemn ceremonies and pledges to not forget the nearly 3,000 people killed. Gary Hershorn/Reuters/Landov hide caption
The North Tower of the World Trade Center collapses on Sept. 11, 2001 Det. Greg Semendinger/NYPD/AP hide caption
Sen. Tom Coburn, R-OK. Win McNamee/Getty Images hide caption
Firefighters make their way through the rubble of the World Trade Center in New York on Sept. 11, 2001. Doug Kanter/AFP/Getty Images hide caption
The World Trade Center towers, on 9/11/2001. Robert Giroux/Getty Images North America hide caption