Soundbreaking: Flight 93 National Memorial architect Paul Murdoch explains his inspiration for the Tower of Voices, a 93-ft-high musical memorial w/ 40 chimes to symbolize the 40 voices of lives lost in the Flight 93 crash on 9/11 in Shanksville, Pa. The video was shot during the "soundbreaking" at the Tower's future location on Sept. 10, 2017.