London has hosted the Olympic Games on two past occasions, in 1908 and 1948, with a third scheduled for 2012. The planned 2012 Summer Olympics will make London the first city to have hosted the modern Games of three Olympiads. London is the only city in the United Kingdom to have ever hosted the Olympics; the United States is the only country to have hosted Summer Olympics on more occasions than the UK. No city in the UK has hosted the Winter Olympic Games.

British participation in Olympic events, both as a competitor and as a host, is the responsibility of the British Olympic Association.

The 1908 Summer Olympics (the Games of the IV Olympiad) were the fourth modern Olympic Games and the third to be hosted outside of Athens, Greece. The International Olympic Committee considers them the fourth Olympic Games, discounting the intercalated 1906 Summer Olympics.

The 1908 Olympic Games were scheduled to take place in Rome, but the eruption of Mount Vesuvius on 7 April 1906 required the Italian government to redirect funds away from the Olympics. The events took place between 27 April 1908 and 31 October 1908, with 22 nations participating in 110 events. The British team easily topped the unofficial medal count, finishing with three times as many medals as the second-place United States.

London ⁱ/ˈlʌndən/ is the capital city of England and the United Kingdom, the largest metropolitan area in the United Kingdom, and the largest urban zone in the European Union by most measures. Located on the River Thames, London has been a major settlement for two millennia, its history going back to its founding by the Romans, who named it Londinium. London's ancient core, the City of London, largely retains its square-mile mediaeval boundaries. Since at least the 19th century, the name London has also referred to the metropolis developed around this core. The bulk of this conurbation forms the London region and the Greater London administrative area, governed by the elected Mayor of London and the London Assembly.

London is a leading global city, with strengths in the arts, commerce, education, entertainment, fashion, finance, healthcare, media, professional services, research and development, tourism and transport all contributing to its prominence. It is the world's leading financial centre alongside New York City and has the fifth-largest city GDP in the world (and the largest in Europe). London has been described as a world cultural capital. It was the world's most visited city during 2011 and London Heathrow is the world's busiest airport by number of international passengers. London's 43 universities form the largest concentration of higher education in Europe. In 2012 London will become the first city to host the modern Summer Olympic Games three times.