London ? Britain fell silent Friday on the first anniversary of the suicide bombing assault on London’s transit system – a stunning strike that killed 52 commuters and wounded more than 700 in the capital’s deadliest attack since World War II.

Prime Minister Tony Blair, survivors and city workers bowed their heads during two minutes of national silence observed from the Wimbledon tennis tournament to Scotland, a quiet punctuated by the solemn tolling of bells at St. Paul’s Cathedral in the heart of London.

Mourners carried flowers and candles to makeshift shrines near the sites of the four bomb blasts. Reflecting the widespread feeling of unease that grips London, one person left a small note that read: “We will never forget.”

“This is a time when our country unites across all races, religions and divides and stands in solidarity with all those who have suffered so much, in sympathy with them and in defense of the values which we share,” Blair said at Fire Brigade headquarters.

Relatives of the dead gathered later for a tearful private ceremony at Regent’s Park, some reading poems to honor their loves ones. Names of all the victims were read one by one as many in the crowd wept and people lined up to place yellow flowers in a mosaic memorial.

Construction workers pause for a two-minute silence in central London's Tavistock Square, site of the bombed No. 30 bus on July 7, 2005. Friday marked the first anniversary of the day four suicide bombers attacked London's transit system, killing 52 commuters and themselves by detonating explosive-laden backpacks on three subway trains and a London bus.

Britain had dealt with Irish Republican Army attacks for decades and had endured the bombing of a U.S. airliner over Lockerbie, Scotland, in 1988 that killed 270 people. But last summer’s bombings plunged Britons into the new era of terrorism that began with the Sept. 11, 2001, attacks – an act that had led Britain to become the strongest ally in the U.S.-led fight against terror.

Britain also was forced to examine the implications of its multiculturalism: All four suicide bombers were young British Muslims – three born in Britain of Pakistani origin and one a Jamaica-born convert who grew up in central England.

One of the London bombers was shown in a video released Friday on the Internet, saying that non-Muslims in Britain had declared war on Islam.

Terrorism committed in the name of Islam has led many to wonder whether, in the post-Cold War era, the world is gripped by another clash of civilizations – one in which the values of Western liberal democracies are in irreconcilable conflict with those of Muslims, whose numbers are growing across Europe.

For Londoners, the attacks have shaken – but not entirely overturned – a conviction that the two cultures can coincide peacefully in the vibrant multicultural capital that is their home.