Olympic rings, mounted on a barge, pass the Tower of London as they move east along the Thames river to celebrate 150 days until the games begin, in London, Feb 28, 2012. [Photo/Agencies]

Yeomen Warders, also known as Beefeaters, are seen through Olympic rings mounted on a barge, as it is positioned in front of the Tower of London on the River Thames in London, Feb 28, 2012. [Photo/Agencies]