Big Ben

  If there is one thing that tourist love to photograph the most in London, it's definately Big Ben.
  On 16th October 1834 a large fire destroyed Westminster Palace and 13 months later the Parliment set up a special comittee that would organise rebuilding of the palace. They announced a competition for desings and the one that eventually won (Charles Barry's project) orginally didn't have a clock tower included. Big Ben first rang on 31st May 1859 but only 4 months later the bell cracked. It was replaced by the lighter one which we can still hear today.

Sources:

http://bigbenfacts.co.uk/history/index.html
http://www.visitlondon.com/things-to-do/sightseeing/london-attraction/big-ben#p0yYGQkM3AhY3Z19.97