London: London Mayor Boris Johnson launched giant Olympic rings measuring 11 meters high and 25 meters wide on the River Thames, to mark 150 days until the start of 2012 Olympics.

The mayor also announced that the city will host a specially commissioned programme of free cultural events to celebrate the Olympics and Paralympics and create "a summer like no other".

"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," Boris Johnson said.

The London Olympics will be held July 27-August 12.

Elsewhere, on the eve of the 150-day countdown, the British Olympic Association (BOA) announced plans for an Olympic Museum to be built on the future Queen Elizabeth Olympic Park (QEOP) as a permanent legacy of the London Games.

The proposals are for the Olympic Museum to open in 2014 and be situated adjacent to the ArcelorMittal Orbit tower. It is expected to become a leading tourist attraction.

The Museum will provide the public with a venue to re-live the excitement, passion and drama of the London 2012 Games.

It is also designed to recognize and celebrate London's unique place in the Olympic Movement as it becomes the first city in the world to host the Olympic Games three times.

BOA believes the museum will ensure the story of London's special Olympic history will be showcased to the world and assets from the 1908, 1948 and 2012 Games are shared with visitors for many years to come.