Family and friends of the British victims of the 11 September attacks have gathered at a sombre ceremony in London to mark the fifth anniversary.
Speeches touched on the bravery of victims' families
Sixty-seven white roses representing each of the victims were laid at the memorial garden near the US Embassy.
A minute's silence at 1346 BST recalled the exact moment when the first plane hit New York's World Trade Center.
A service also took place at the British Memorial Garden in Manhattan, which will open next year.
The event at London's own memorial garden, in Grosvenor Square, was organised by the US embassy.
Culture Secretary Tessa Jowell, who was given special responsibility for co-ordinating support for relatives of the British victims, represented the UK government.
In a short speech, Ms Jowell paid tribute to the bravery and strength of the families.
"In the years since, perhaps some of the rawness has healed. This garden has become a place of peace and remembrance," she said.
She laid a wreath in the garden before the 80 or so relatives, as did US Ambassador Robert Tuttle.
Investment bank Cantor Fitzgerald, which lost hundreds of employees, sent a large bouquet of lilies.
Speaking at the ceremony, Alex Clarke, chair of the September 11 Families Support Group, said the loss of her daughter, Suria, in the attack had never got any easier.
"What's five years? To us, I think it is just the same. The pain is always going to be there."
Jim Cudmore, treasurer of the group, said it had been a lovely day but some relatives missed the speeches because of heightened security around the US Embassy.
Later in the day, opposition leader David Cameron, carrying a large bouquet of white lilies and roses, visited the garden to pay his respects.
A free concert took place in the square in the evening with performances by 14-year-old singer Daisy Blue, from Swansea, and soprano Elin Manahan.
Speaking at the British Memorial Garden in New York, Prince Andrew said terrorism would never cause people to turn their backs on their core values.
"These bonds cannot nor will not be undone by those who stand for intolerance and hate."
Solidarity with US
He earlier said that he had a small insight into the anguish families suffered on the day, when he was unable to contact the Duchess of York.
She had been planning to visit her charity office in the World Trade Center on the afternoon of 11 September.
Patricia Bingley, 72, from Clacton-on-Sea, Essex, had flown to New York to remember her son Kevin Dennis, who was killed in the twin towers.
After the service at the British Memorial Garden, which she watched with her husband Terry, she said: "It seems like it's going to be a little English garden which we need here in New York for when British relatives come over.
"Prince Andrew had a chat with me and he was really nice.
"I feel much closer to my son here in New York, it's more comforting."
The memorial garden, just half a mile from where the strikes took place, will formally open next year.
Some 120 British police officers flew to New York at their own expense for the anniversary to show solidarity with US counterparts who lost their lives.
Thousands of City workers held a minute's silence and cricketer Shane Warne and rugby player Martin Johnson answered the phones on the trading floor of brokers BGC where revenue from the day's trading will go to charity.
And in Hayle, Cornwall, family and friends of British-born Rick Rescorla, who died after helping people leave the World Trade Center's South Tower, gathered at the town's memorial to him.