Americans are remembering the victims of the September 11, 2001 attacks with a 15th anniversary ceremony which included the recital of their names, tolling church bells and a tribute in lights at the site where New York City's massive twin towers collapsed.
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 3000 victims killed in the worst attack on US soil since the 1941 bombing of Pearl Harbour.
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 died when the first plane struck the north tower just below where they worked on the 101st to 105th floors.
Angela Checo honoured 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 DC, 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 honour 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.
At the Pentagon, a trumpet played as US President Barack Obama took part in a wreath-laying ceremony.
"Fifteen years may seem like a long time. But for the families who lost a piece of their heart that day, I imagine it can seem like just yesterday," Obama said.
No public officials spoke at the New York ceremony, in keeping with a tradition that began in 2012.
But many dignitaries attended, including Republican presidential hopeful Donald Trump and his Democratic rival Hillary Clinton.
As evening falls across New York City on Sunday, spotlights will project two giant beams of light into the night sky to represent the fallen twin towers, fading away at dawn.
In the twin towers' place now rises the 104-storey 1 World Trade Center. Also known as the Freedom Tower, it is the tallest skyscraper in the Western Hemisphere, at 541 metres.
In Kabul, the top American commander in Afghanistan, General John Nicholson, paid tribute to members of the NATO-led coalition and Afghan security forces who had been killed since the Taliban regime fell.