Family members of victims of the Sept. 11 attacks demonstrate against the decision to transfer the unidentified remains to a repository at the World Trade Center site. Eric Thayer /Reuters /Landov hide caption

itoggle caption Eric Thayer /Reuters /Landov

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

itoggle caption 911memorial.org

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

itoggle caption Gary Hershorn/Reuters/Landov

A runner heads down the banks of the Charles River in Cambridge, Mass., in front of the Boston skyline at dawn, the morning after deadly explosions at the Boston Marathon. Charles Krupa/AP hide caption

itoggle caption Charles Krupa/AP