Big Ben

Big Ben is the largest of the tower's five bells and weighs 13.5 long tons. It was the largest bell in the United Kingdom for 23 years. The origin of the bell's nickname is open to question; it may be named after Sir Benjamin Hall, who oversaw its installation, or heavyweight boxing champion Benjamin Caunt. Four quarter bells chime at 15, 30 and 45 minutes past the hour and just before Big Ben tolls on the hour. The clock uses its original Victorian mechanism, but an electric motor can be used as a backup.

The tower is a British cultural icon recognised all over the world. It is one of the most prominent symbols of the United Kingdom and parliamentary democracy, and it is often used in the establishing shot of films set in London. The clock tower has been part of a Grade I listed building since 1970 and a UNESCO World Heritage Site since 1987.