Big Ben is a four-sided clock tower which is part of The Palace of Westminster, on the banks of the River Thames in Westminster, London. In 2009, Big Ben celebrated its 150 year anniversary.
The name Big Ben was intended for only the Great Bell in the belfry (the largest bell of five), but is now commonly used to refer to the tower, the clock and the bell.
Two other towers existed before the construction of the current structure began in 1843. The first was built 1288 to 1290; the second replaced the first in 1367 and existed until 1707 when it was pulled down due to disrepair. A sundial was put in the towers place.
The clock tower took 13 years to build, 1843 to 1856, and stands at 316 feet tall. There are 11 floors to the tower and 334 steps to the belfry.