Relatives of the 52 victims of the July 7 bombings marked the fourth anniversary of the attacks with the unveiling of a memorial commemorating their loved ones.
They were joined by the Prince of Wales, Prime Minister Gordon Brown and other political leaders as the nation remembered those killed and injured in the atrocities on London's transport network in 2005.
A monument honouring the dead and costing nearly £1 million has been created in Hyde Park - 52 stainless steel columns, or stelae, 11.5ft (3.5m) tall.
Each one is unique and they have been grouped together in four clusters, reflecting the separate locations of the bombings - Tavistock Square, Edgware Road, King's Cross and Aldgate. Four suicide bombers detonated their rucksack devices near these locations on the morning of July 7 2005, killing the 52 and injuring hundreds of others, some seriously.
A stainless steel plaque naming all those who died has also been erected at the memorial site between the park's Lover's Walk and Park Lane.
Meanwhile, MPs have launched a major new inquiry into the July 7 bombings on the anniversary of the attacks.
The House of Commons Home Affairs Committee is expected to call senior intelligence officials to give evidence.
In its report on the Government's anti-terror strategy, the committee warned the London Underground was still "extremely vulnerable" to terrorist attack.
Committee chairman Labour MP Keith Vaz said: "Following this report we will now embark on a new inquiry into the 7/7 bombings."
He said MPs would begin by looking at how Cobra, the Cabinet Office's emergency committee, responded to to attacks. It follows criticism of the committee by former Scotland Yard counter-terror boss Andy Hayman.
