London - Big Ben Tower

The Houses of Parliament and the clock tower are one of London's iconic landmarks. The building is known as the Palace of Westminster and the clock tower is sometimes called St Stephen's Tower, although it is commonly referred to as Big Ben. Big Ben is actually the massive bell inside the clock tower, which weighs in at over 13 tons (13,760 kg).

The Clock Tower
The clock tower looks spectacular at night when the four clock faces are illuminated. Each dial is 23 feet square, the minute hand is 14 feet long and the figures are two feet high. A special light above the clock faces is also illuminated, letting the public know when parliament is in session.
Big Ben's timekeeping is strictly regulated by a stack of coins placed on the huge pendulum. Big Ben has rarely stopped and even after an incendiary bomb destroyed the Commons chamber during the Second World War. The clock tower survived and Big Ben continued to strike the hours.
The chimes of Big Ben were first broadcast by the BBC on 31 December 1923, a tradition that continues to this day.
Big Ben History
The Palace of Westminster was destroyed by fire in 1834. In 1844, it was decided that the new buildings for the Houses of Parliament should include a tower and a clock. The bell was refashioned in Whitechapel in 1858 and the clock first rang across Westminster on 31 May 1859.
Just two months later, Big Ben cracked. A lighter hammer was fitted and the bell rotated to present an undamaged section to the hammer. This is the bell as we hear it today.
Why Ben?
The origin of the name Big Ben is not known, although two different theories exist.
The first is that is was named after Sir Benjamin Hall, the first commissioner of works, a large man who was known affectionately in the house as 'Big Ben'.
The second theory is that it was named after the champion of the prize ring at that time, Benjamin Caunt. Also known as 'Big Ben' this nickname was commonly bestowed in society to anything that was the heaviest in its class.
Visiting Big Ben
The clock tower is not open to the general public. However, it is possible for UK residents to arrange a visit by writing to their MP. Applications should be made in writing, as far in advance as possible, to:
House of CommonsWestminsterLondonSW1A 0AA
It is not possible for overseas visitors to tour the clock tower.

This information is from http://www.visitlondon.com/attractions/culture/big-ben