As classical music drifted across the 9/11 Memorial plaza in lower Manhattan, family members and first responders slowly read the names and delivered personal memories of the almost 3,000 victims killed in the worst attack on U.S. soil since the 1941 bombing of Pearl Harbor.
Relatives in the crowd embraced and some held photos of loved ones and signs that read: "Never to be forgotten," "We miss you," and "Gone too soon."
Tom Acquarviva's 29-year-old son Paul was one of 658 employees of financial services firm Cantor Fitzgerald who perished after the first plane struck the north tower just below where they worked on the 101st to 105th floors.
"Not a day goes by that we don't remember him," Acquarviva told Reuters.
Angela Checo honored her brother, Pedro Francisco, 35, who was a vice president at investment and wealth manager Fiduciary Trust on the 96th floor of the south tower.
"He was coming down but forgot someone and went back upstairs to save them," Checo said. "That's why he never made it down."
The ceremony paused for six moments of silence: four to mark the exact times four hijacked planes were crashed into the World Trade Center, the Pentagon near Washington D.C., and a Pennsylvania field. The last two record when the North and South towers of the Trade Center crumpled.
It was held by two reflecting pools with waterfalls that now stand in the towers' former footprints, and watched over by an honor guard of police and firefighters.
More than 340 firefighters and 60 police were killed on the that sunny Tuesday morning in 2001. Many of the first responders died while running up stairs in the hope of reaching victims trapped on the towers' higher floors.