Across Europe other cities, too, fell silent - some with their own horrific memories of similar atrocities.
On London Underground many staff wore black armbands as a mark of respect, and on mainline stations, in shops and offices, work ceased as the carnage of a week ago was recalled.
Airports came to a standstill, taxis pulled over to the sides of roads and many heeded the appeal for people to leave their workplace to stand on the street in silent tribute to the 52 victims of the bombings.
The Queen stood in silence in the forecourt of Buckingham Palace.
The Prime Minister observed the silence in the garden of No 10, where he had been presenting bravery awards to police officers.
At Scotland Yard, the Home Secretary Charles Clarke, stood with the Metropolitan Police Commissioner Sir Ian Blair for the two minutes silence.
Hundreds of Scotland Yard staff lined the street outside the Met's headquarters for the silence, the start and end of which was announced by a police siren.