America remembers 9/11 (29 images)

A boy holds a photo of the Twin Towers near the Reflecting Pools at the 9/11 Memorial near One World Trade Center on the 15th anniversary of the terrorist attacks on the World Trade Center at Ground Zero in New York City on September 11, 2016. Photo by John Angelillo/UPI

Mourners and men in uniform gather and lay flowers at the Reflecting Pools at the 9/11 Memorial near One World Trade Center on the 15th anniversary of the terrorist attacks on the World Trade Center at Ground Zero in New York City on September 11, 2016. Photo by John Angelillo/UPI

A visitor to the Wall of Names at the Flight 93 National Memorial reaches out to touch the name of Mark David Rothenberg on the 15th anniversary of the the crash of the Flight 93 on September 11, 2016. Photo by Archie Carpenter/UPI

Democratic candidate for President Hillary Clinton stands near the Reflecting Pools at the 9/11 Memorial near One World Trade Center on the 15th anniversary of the terrorist attacks on the World Trade Center at Ground Zero in New York City on September 11, 2016. Photo by John Angelillo/UPI