A participant of the 2016 National Capital Region 9/11 Memorial Stair Climb and 5K Walk climbs the stairs of the Gaylord National Resort and Convention Center at National Harbor, Md., Sept. 10, 2016. In honor of the 343 firefighters who lost their lives in the terrorist attacks on Sept. 11, 2001, more than 600 local community members either climbed 110 flights of stairs or walked a 5K. (U.S. Air Force photo by Airman 1st Class Valentina Lopez)