The victims and survivors of the 7 July London bombings have been honoured in a national memorial service at St Paul's Cathedral in London.
The Queen led the congregation of 2,300 at St Paul's Cathedral
Candles were lit to represent the four bombing sites and prayers said for all involved, including the emergency workers who dealt with the aftermath.
The Archbishop of Canterbury told the service: "Those who so pointlessly and terribly died were...non-replaceable."
The Queen and Tony Blair joined the bereaved families and blast survivors.
Transport workers, senior politicians and police officers were also among the 2,300-strong congregation.
The attacks by four suicide bombers killed 52 people and injured hundreds.
In a moving sermon Dr Rowan Williams said: "We are here grieving, after all, because those who so pointlessly and terribly died were, each one of them, precious, non-replaceable".
He continued: "Those who suffered injury and deep trauma and loss are likewise unique, their minds and hearts scarred by this suffering.
"Time gives perspective and may bring healing; but the trauma of violence, and even more the death of someone we love, makes a difference that nothing will ever completely unmake."
He spoke of the fear caused by the randomness of terrorist violence.
"It really doesn't matter who you are, what you have done or not done, what you think and believe, you are still a target just by being where you are at a particular time."
Four candles were lit in a poignant Act of Remembrance - one for each of the four blast sites at Aldgate, King's Cross, Edgware Road and Tavistock Square.
The Christian service was planned to emphasise the multi-faith nature of London and the bombing victims.
Dr Williams said the faiths had responded to the tragedy together.
A "candle of hope" was also lit by a 15-year-old Sikh, an 11-year-old Buddhist, a 15-year-old Jew, a 12-year-old Hindu, a 14-year-old Muslim and an 18-year-old Christian.
Prayers were then offered for the emergency services first on the scene.
The Dean of St Paul's, the Very Rev Dr John Moses gave thanks for the lives of those who died, as well as remembering "the victims of terrorism all over the world".
"We pray for all who mourn, for all who are rebuilding their lives and we give thanks to those who shared, often at great cost to themselves, in the work of rescue and rehabilitation.
"We remember in particular the staff of Transport for London, the police, the paramedics, the doctors and nurses of London hospitals, clergy and faith leaders, all men and women of goodwill who assisted in any way."
More than half of the congregation had lost a family member or friend or had been injured in the blasts.
Many relatives said it was painful event, but were glad they had attended.
Janet Foulkes, whose 22-year-old son David died in the Edgware Road blast, said she was still in tears "every day".
But she added she had found some comfort in the "calm and peaceful" service.
Garri Holness, who lost a leg in the King's Cross bombing, said he found the service very moving.
"A lot of things came together, it has been a very important day for me," he said.
Mr Holness said that while seated in the cathedral he remembered more details from 7 July. He said he recalled boarding the train and commenting to another passenger about how busy it was.
Mr Holness spoke to Mr Blair, who spent some time talking to survivors and bereaved relatives.
After the ceremony the Queen also met some of the relatives of those who died.
Seven-year-old Ruby Gray, from Ipswich, whose father Richard was killed in the Aldgate blast, presented her with a posy.
Others at the service included the Duke of Edinburgh, Deputy Prime Minister John Prescott, Chancellor Gordon Brown, Opposition leader Michael Howard, Liberal Democrat leader Charles Kennedy, London mayor Ken Livingstone and Metropolitan Police Commissioner Sir Ian Blair.
Cardinal Cormac Murphy-O'Connor led the prayers of remembrance and thanksgiving.