Airman 1st Class Devin Oliver, 436th Civil Engineer Squadron fire protection apprentice, lays a wreath during the 19th Anniversary 9/11 nemorial event Sept. 11, 2020, at Dover Air Force Base, Delaware. A 9/11 memorial sculpture at the Air Mobility Command Museum adjacent to the base includes two pieces of steel from the World Trade Center, a rock from the United Airlines Flight 93 crash site and a block from the damaged portion of the Pentagon. (U.S. Air Force photo by Mauricio Campino)