Running till Sep 9, the 25,000 artists will be from all 204 competing Olympic and Paralympic nations.
In Stirling city in Scotland, world-famous conductor Gustavo Dudamel will lead “The Big Concert” with the Simon Bolivar Symphony Orchestra of Venezuela, an official statement said.
Lake Windermere, in Cumbria county in northwest Britain, will host the “On the Nightshift” programme, a free outdoor pyrotechnic and percussion extravaganza.
A gigantic ship called “The Voyage” will sail into Birmingham, accompanied by dancers and aerial performers.
In Derry in Northern Ireland, singers Pixie Lott and Imelda May will lead the free “Peace One Day” concert, produced by Peace One Day founder Jeremy Gilley and actor-ambassador Jude Law.
At the festival in Wales, artist Jeremy Deller’s life-size inflatable replica of Stonehenge, called “Sacrilege”, will for the first time be shown at the National Botanical Gardens in Carmarthen. The artwork will travel to many locations during the festival.
There will be 12,000 events, with performances at 900 villages, towns and cities all over the country. More than 10 million free tickets are there to be won.
Ruth Mackenzie, director for the Cultural Olympiad and London 2012 Festival, said: “When Britain won the bid for the Olympics in 2005, we promised to return to Baron Pierre de Coubertin’s original idea of an Olympic Games based on the three pillars of sport, art and education.”
“This summer, London 2012 Festival showcases the world’s greatest artists alongside the stars of the sports world, a once-in-a-lifetime cultural experience to match the once in a lifetime visit of the Olympic and Paralympic Games to Britain.”