The festival, which runs from June 21-September 9, is the culmination of the four-year Cultural Olympiad, and organisers said on Tuesday there would be 10 million free tickets for people to experience dance, theatre, art, music and more.

Culture Secretary Jeremy Hunt said he hoped to raise public awareness about thousands of events happening up and down the country as excitement ahead of the July 27-August 12 Games built.

"This is a really huge moment," he said on Tuesday. "I don't think the penny has yet dropped with the public.

"I think they're beginning to appreciate the scale and excitement of the Games, but the scale and excitement of the biggest cultural festival in our history is something ... I think people have yet to appreciate."

He said the festival, which cost around 55 million pounds to organise, was a chance to showcase Britain's cultural heritage.

"Not just in 2012 but every year we have the best culture in the world in this country and this is our big opportunity to bang the drum."

Some events officially counted as part of the Cultural Olympiad would have happened anyway, but many have also been put on especially for the programme.

To mark the opening of the festival, Venezuelan conductor Gustavo Dudamel will lead the Simon Bolivar Symphony Orchestra of Venezuela in an open-air concert set against the backdrop of Scotland's Stirling Castle.

Also on Thursday, French pyrotechnic company Les Commandos Percu will stage a spectacular outdoor firework show on the shores of Lake Windermere in northwest England to coincide with the Olympic Torch Relay.

Among the more bizarre events launching the festival will be artist Jeremy Deller's life-sized replica of Stonehenge called "Sacrilege".

Part artwork, part bouncy castle, it will "pop up" at the National Botanical Gardens at Carmarthen in Wales and then go on a tour of the United Kingdom.

Peace One Day, an organisation dedicated to the idea of one day a year free of conflict, is staging a concert in Londonderry, Northern Ireland, and Yoko Ono's "Imagine Peace" art installation will be unveiled on London 2012 screens.

One of the biggest events of the opening week will be Hackney Weekend, sponsored by the publicly funded BBC Radio 1, a free live music event across six stages with over 100 artists appearing including Jay-Z, Rihanna and Jessie J.

Around 100,000 people are expected at the free London gig.

Ruth Mackenzie, director of the Cultural Olympiad and London 2012 Festival, said she hoped the budget would be justified by the level of public interest.

The Olympiad has been criticised for being unfocused - a poll earlier this year showed most Britons did not know exactly what it was - and some of the projects have been derided as pretentious and costly.

"The festival funding is an investment ... rather than a fund and it's an investment of 55 million pounds.

"Some of you might think it's a lot, but I assure you, for a 12-week festival over the entire United Kingdom ... (it) is a pretty small investment and I hope that when we do the final figures after the festival we are able to demonstrate pretty good value for money." (Reporting by Mike Collett-White, editing by Paul Casciato)

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