The 2012 Summer Olympics was an international multi-sport event held from 27 July to 12 August 2012 in London, England, United Kingdom. The first event, the group stage in women's football, began on 25 July at the Millennium Stadium in Cardiff, followed by the opening ceremony on 27 July. 10,768 athletes from 204 National Olympic Committees participated.
Following a bid headed by former Olympic champion Sebastian Coe and the incumbent 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 became the first city to host the modern Olympics three times, having previously hosted the Summer Games 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 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.