Giant Olympic rings sailed down the River Thames today bringing with them details of the biggest arts festival London has ever seen.

Standing at 11 metres high by 25 metres wide, the five interlinked rings has been travelling since 7am this morning = on a barge from Battersea Bridge to the Thames Barrier at Silvertown.

Mayor of London Boris Johnson officially announced this summer’s cultural programme as the iconic Olympic Rings arrived at Tower Bridge around 1.30pm to mark 150 days to go until the Opening Ceremony in Stratford.

He described London culture and creativity as “a hugely important part of our economy.”

Mayor Johnson added: “From museums to theatre, and music to design, we have a reputation that is second to none and London’s finest artists and organisations are producing an exceptional range of brand new cultural events that will add to the excitement of hosting the Games.

“We’re creating the biggest festival of outdoor arts ever to be seen in the capital, as well as fantastic new work that will throw new light on some of our city’s lesser known landmarks and hidden gems.

“Whereever you are you will feel a part of the 2012 celebrations and experience a summer like no other in one of the most exciting cities on earth.”

From July 21 to September 9, every London borough will come alive with free music, theatre, art and dance to complement the BT London Live events in Hyde Park, Victoria Park and Trafalgar Square.

The vast, diverse programme includes Showtime, London’s biggest outdoor arts festival where 25 companies will tour local town centres, high streets and parks; surprise, one-off, pop-up performances; a transformation of iconic landmarks with projections on to buildings, bunting and banners; and London’s bridges from Hungerford Bridge in the west to Tower Bridge in the east will light up with dazzling displays of colour in the evenings.

Leading artists will also show visitors Hidden London by transforming nooks and crannies including canals, lidos and cemeteries while further exploration can be found on Discovery Trails in the north, south, east, west and central London and there will be a parade of Team GB Athletes through the streets.