In this Sept. 9, 2018, file photo, people attending the dedication stand around the 93-foot tall Tower of Voices at the Flight 93 National Memorial in Shanksville, Pa., where the tower contains 40 wind chimes representing the 40 people that perished in the crash of Flight 93 in the terrorist attacks of Sept. 11, 2001. Victims' relatives, survivors, rescuers and others attended Tuesday's Sept 11 Anniversary ceremony at the World Trade Center. President Donald Trump and first lady Melania Trump joined an observance at the new Shanksville, tower honoring victims, and Vice President Mike Pence attended a ceremony at the Pentagon.