The year began with the fatal stabbing of a 17-year-old and by the end of the year 25 other teenagers, the youngest aged just 14, had been killed.
Police acted quickly to avert two attempted car bombings in central London.
A fire ravaged Cutty Sark, the historic tea clipper in Greenwich, as it was undergoing a £25m conservation.
A police watchdog said the Metropolitan Police made serious and avoidable errors in killing Brazilian Jean Charles de Menezes who was mistaken for a suicide bomber.
A National Express coach overturned on a slip road near Heathrow killing three people.
Banaz Mahmod was strangled and buried in a suitcase in Birmingham after her family found she had a boyfriend. Her father Mahmod Mahmod, and two others were jailed for life.
Hundreds of residents protested as the congestion charge zone was extended to west London.
Nearly 2m spectators lined the city's streets to watch the start of the Tour de France. The event brought in £120m to the city's economy.
The jagged logo for the 2012 Olympic Games in London was met with mixed reviews. The design for the 80,000 stadium was also unveiled.
Anthony Joseph, a paranoid schizophrenic, admitted stabbing passenger Richard Whelan to death on a bus when he confronted Joseph for throwing chips at his girlfriend.
Thousands of people set up camps near Heathrow airport in a week-long protest against the airport's expansion plans.
A 9ft-high statue of former South African President Nelson Mandela was unveiled by him. The bronze statue stands at Parliament Square.
The Queen opened St Pancras International railway station which underwent a £800m revamp.
More than 130 items excavated from the tomb of Egyptian boy King Tutankhamun went on display. Tutankhamun's treasures have returned to the city after 35 years.
Steve Harland, from Didcot, Oxfordshire, became the 25 millionth visitor to ride the iconic London Eye. The 450ft-high attraction was opened seven years ago.