У меня есть газета про историю Биг Бена на английском, там говорится о том,

What is Big Ben?
Big Ben is the symbol of Great Britain and one of the most beautiful sights of London. It’s the largest and the most famous clock in the world. 
Originally, Big Ben is a tower. It’s one of the highest towers of Westminster Palace. Big Ben is very popular with spectators, nobody is allowed inside the tower. But if you are lucky, you can hear how the bell stricks.
Officially, the clock has started its work on 31 May 1859. Big Ben is the huge bell inside the building. Its weight is about 13 tones and its rings every hour daily: once at one o’clock, twice at two o’clock and so on. 
There are many hypotheses for the origin of the name Big Ben. The most popular one suggests that the bell was named after Sir Benjamin Hall, who was responsible for the installation. Some of people say he was really tall and that’s why this bell is called big.