Postcards are displayed for sale in front of the Big Ben Clock Tower above the Houses of Parliament in London May 30, 2009. Commonly called Big Ben, which is actually the nickname of the bell inside it, the 96-metre Clock Tower looks down on the Houses of Parliament along the River Thames and has become a symbol of stability, endurance and democracy in Britain. It was 150 years ago on Sunday that the four-faced Great Clock started keeping time, and on July 11, 1859, Big Ben first struck time. REUTERS/Luke MacGregor (BRITAIN ANNIVERSARY POLITICS SOCIETY IMAGES OF THE DAY)