Nelson Mandela urges world leaders not to "look the other way" from poverty during a mass rally.
Water fountains are dyed green as part of the annual St Patrick's Day Parade and Festival.
The square's infamous pigeon population waned after a by-law was introduced banning people from feeding them.
Katherine Jenkins sings for veterans and music fans at a concert to mark the 60th anniversary of VE day.
Thousands of people celebrate as news comes through from Singapore that London will host the 2012 Olympic Games.
An expanse of the square disappears under a carpet of 95,000 bedding plants to promote French wine.
Thousands turn out to join the victory celebrations of England's cricket team, fresh from winning back the Ashes.
A dramatic sound and light show ends celebrations for the 200th anniversary of the Battle of Trafalgar.
Friends are moved to tears as they watch a memorial service for the victims of the July bombs broadcast on a giant screen.
Londoners and visitors merge in the square to see in the start of 2006.