Seven-year-old Alex Pitz-Giannetti came with his mother to visit Pepperdine University’s annual Waves of Flags installation that commemorates the nearly 3,000 lives lost in the 2001 terrorist attacks. (Al Seib / Los Angeles Times )
Cynthia Votava helps straighten flags at Pepperdine University’s Waves of Flags installation, which she has attended for the last eight years. (Al Seib / Los Angeles Times )
The south pool of the National September 11 Memorial on the 18th anniversary. (Justin Lane / EPA/Shutterstock)
People observe a moment of silence during ceremonies at the National September 11 Memorial in New York City. (Spencer Platt / Getty Images )
A visitor pauses by the glade as people attend the ceremony at the World Trade Center site. (Don Emmert /AFP/Getty Images)
Firefighters and police officers participate in the start of ceremonies at the National September 11 Memorial. (Spencer Platt / Getty Images)
Alexandra Hamatie, whose cousin Robert Horohoe was killed on Sept. 11, pauses at the National September 11 Memorial during a morning commemoration ceremony for the victims. (Spencer Platt / Getty Images)
New York City firefighters stand as an honor guard in front of a memorial for the 343 firefighters who died on Sept. 11, near the National September 11 Memorial in New York. (Justin Lane / EPA/Shutterstock)
Visitors to the Flight 93 National Memorial near Shanksville, Pa., participate in a sunset memorial service as the nation prepared to mark the anniversary of the 2001 attacks. (Gene J. Puskar / Associated Press)
A visitor to the Flight 93 National Memorial in Shanksville, Pa., views the Wall of Names. (Gene J. Puskar / Associated Press)
A Marine stands at the Pentagon Memorial for a remembrance ceremony in Arlington, Va. (Pete Marovich /EPA/Shutterstock)
President Trump and First Lady Melania Trump are joined by survivors, victims’ families and White House staff as they acknowledge a moment of silence at 8:46 a.m. EDT, the time the first plane struck the north tower of the World Trade Center on Sept. 11, 2001. (Alex Wong / Getty Images)
