Britain will this week mark the 10th anniversary of the July 7 terrorist attacks.
Days after observing a minute's silence for the victims of the Tunisia beach massacre, the country will fall silent again in memory of the 52 people killed in the atrocity in London a decade ago.
The period of reflection - to take place at 11.30am on Tuesday during a service at St Paul's Cathedral attended by the Duke of York - will be observed across the capital's public transport network.
Announcements will be halted and bus drivers asked to bring vehicles to a stop if they can do so safely.
Transport for London said Tube services would run as normal but passengers would be asked to observe the silence and platform and other announcements would be halted for the duration.
Survivors, relatives of the dead and members of the emergency services have been invited to the commemorative event.
Wreaths will be laid beforehand at the permanent Hyde Park memorial to the outrage, where a second service, to be attended by the Duke of Cambridge, will take place later, featuring music, a series of readings and the laying of flowers.
July 7 2005 had dawned with London still elated from learning the previous day that it had won the 2012 Olympics, but the euphoria was short-lived.
Suicide bombers Mohammed Sidique Khan, 30, Shehzad Tanweer, 22, Hasib Hussain, 18, and Jermaine Lindsay, 19, met at Luton station that morning.
They took a train to King's Cross in London, then hugged and separated to carry out their deadly missions.
Within three minutes of 8.50am, Tanweer detonated his bomb at Aldgate, Khan set his device off at Edgware Road and Lindsay blew himself up between King's Cross and Russell Square.
Hussain detonated his device on board the number 30 bus at Tavistock Square at 9.47am.
Twenty-six died in the bombing at Russell Square on the Piccadilly line, six in the bombing at Edgware Road on the Circle Line, seven in the bombing at Aldgate on the Circle Line and 13 in the bombing on the number 30 bus at Tavistock Square. Hundreds more were injured.
A fortnight later, another four would-be suicide bombers launched failed attacks on the Tube and a bus, leading to police marksmen shooting dead innocent Brazilian Jean Charles de Menezes.
The threat of terrorism 10 years later was horrifyingly demonstrated last month when a gunman murdered 38 people, including 30 Britons, in the Tunisian resort of Sousse.