Probably the most famous sight in London, the tower that adjoins the Houses of Parliament, whilst commonly referred to as "Big Ben", is actually simply named the "Clock Tower".

"Big Ben" is the name of the main 13.5 tonne bell, whose tolling tune is instantly recognisable.

The world's largest four-faced chiming clock, the Tower is 96 metres high and each clock face is seven metres in diameter. The clock's pendulum is just less than four metres long and weighs over 300 kilograms.

The Clock Tower is the main focus of the countdown to a New Year throughout the UK, with TV pictures beaming live across the world.

Within the Tower is a small prison room, which can be used to incarcerate members of the House of Lords or the House of Commons for unruly behaviour. The last MP to have stayed here did so in 1880 after refusing to swear an oath to Queen Victoria.

UK residents can arrange a tour of the Clock Tower through their local MP, although overseas visitors cannot currently enter the Tower.

Further information:

• Houses of Parliament
• History of Parliament
• House of Commons
• House of Lords
• State Opening of Parliament