Big Ben is not open to the public. Possibly the most famous clock face and chimes in the world, Big Ben is actually the name of the biggest bell (13.5 tons) inside The Clock Tower (320ft) which forms part of the Houses of Parliament.Built in 1858/9 the bell was named after one Sir Benjamin Hall and when it was cast it was Britain's heaviest bell.
The clock's four dials each have a diameter of 23ft, the minute hands are 14ft long and the numerals on each face are nearly 2ft high. The placing of old pennies in the mechanism controls the accuracy of the clock movement, yet it is incredibly accurate.
The tower which houses Big Ben has been called by many names, one of the most popular is St Stephen's Tower. The official line, from the Head of Public Information at the Palace is that the Clock Tower is simply called The Clock Tower. However, the name Big Ben has now passed into every day use and the locals call it Big Ben so we'll go along with that too.
There is a light at the top of the tower which, when lit, indicates that the House of Commons is sitting. During the day you can tell if they're sitting by looking for a flag at the top of the nearby Victoria Tower, which is the tallest and largest of the Westminster towers.
The subject of John Buchan's '39 Steps', the Clock Tower is unfortunately not open to the public so you won't be able to check how many steps actually lead to the belfry.
However, we can tell you that it is not 39 - It is actually closer to 400 depending on where you start and finish.
It is widely thought that Buchan dreamt up the idea of using 39 steps at a time when he was recovering from illness in a convalescent home. Directly outside his windows there were 39 steps leading from the patio to the lawn!
The room that houses the actual clock mechanism is full of Victorian mechanical wonders that whiz and band each time the clock strikes.
The ding-dongs that precede the striking of the hour were taken from George Frederick Handel's 'Messiah' and actually have lyrics too.
'All through this hour,
Lord be my guide,
That by thy power,
No foot shall slide.'
The clock plays the first line at a quarter past the hour, the first and second lines on the half hour, three lines at a quarter to and the whole lot on the hour!
Address: Houses of Parliament, Parliament Square, Westminster, London, SW1A 2NE