The 2012 Summer Olympics, formally the Games of the XXX Olympiad and commonly known as London 2012, was a major international multi-sport event celebrated in the tradition of the Olympic Games, as governed by the International Olympic Committee (IOC). It took place in London and to a lesser extent across the United Kingdom from 25 July to 12 August 2012. The first event, the group stage in women's football began on 25 July at the Millennium Stadium in Cardiff, followed by the opening ceremonies on 27 July. 10,768 athletes from 204 National Olympic Committees (NOCs) participated.

Following a bid headed by former Olympic champion Sebastian Coe and then-Mayor of London Ken Livingstone, London was selected as the host city on 6 July 2005 during the 117th IOC Session in Singapore, defeating bids from Moscow, New York City, Madrid, and Paris. London is the first and only city thus far to host the modern Olympic Games three times, having previously done so in 1908 and in 1948.

Construction for the Games involved considerable redevelopment, with an emphasis on sustainability. The main focus was a new 200-hectare (490-acre) Olympic Park, constructed on a former industrial site at Stratford, East London. The Games also made use of venues that already existed before the bid.

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