Giant Olympics rings launched on River Thames

Giant Olympic rings floated down the Thames River in London to mark 150 days until the start of the Summer Games.

The five iconic rings, measuring 36 feet (11 meters) tall, were unveiled on a barge Tuesday as a tug boat pulled them toward the historic Tower Bridge. The Olympic symbol traveled east to the Thames Barrier before returning to Tower Bridge.

London Mayor Boris Johnson launched the spectacle as he announced free cultural and entertainment events that will be held in London this summer to welcome the millions of visitors arriving for the Olympics.

The games run from July 27 to Aug. 12.