Big Ben is the name popularly applied to the clock tower in London. However, it is actually the nickname for the exceptionally large hour bell installed inside the tower.
The Big Ben tower project was completed on April 10, 1858 and is still working properly. In 1856 the large bell was cast, but it was broken before it could be installed. The replacement bell was cast in 1858, but the hammer inside the bell cracked it in 1859. They simply turned the bell and made the hammer smaller to prevent any more damage, and Big Ben was considered finished.
The original bell, weighing 16 tons, was cast on August 6, 1856, by John Warner and Sons, in Stockton-on-Tees. The bell was apparently named after Sir Benjamin Hall, whose name was inscribed on it. Unfortunately, the bell cracked beyond repair during testing and a replacement had to be fashioned.
The replacement bell (made partly from the old one) weighs 13.5 tons, and was fashioned at Whitechapel Bell Foundry in 1858. It took 18 hours to pull the bell 200 ft up to its resting place in the Clock Tower's belfry. It is 2.2 metres tall and 2.9 metres wide. This new bell first chimed in July 1859. Only two months after it was installed, it too cracked.
According to the foundry's manager, George Mears, the clock designer (Edmund Denison) had used a 672-pound hammer, more than twice the maximum weight specified. For three years Big Ben was taken out of commission and the hours were struck on the lowest of the quarter bells until it was reinstalled. To make the repair, a square piece of metal was chipped out from the rim around the crack, and the bell turned so the new hammer struck in a different place. Big Ben has chimed with a slight distortion ever since. The bell is still in use today complete with the crack.
In 2012 the tower was renamed 'The Queen Elizabeth Tower' ('Elizabeth Tower') in celebration of the Queens Diamond Jubilee.