clipped from: news.bbc.co.uk 
The clock tower in Parliament Square, Westminster, is being given a spring clean following a year of activities in recognition of the landmark.
Technically Big Ben refers only to the clock's largest bell, but has become synonymous with the clock tower itself.
The bell, cast in Whitechapel on 10 April 1858, was first rung in the Great Westminster Clock on 31 May 1859.