The Clock Tower, often wrongly referred to as Big Ben, is one of the most well known towers in the world. At the other end of the Palace if Westminster is the Victoria Tower . It is 98m (323 ft) high - with a flagstaff adding a further 22m. It was not merely built to provide symmetry to the New Palace - but was custom designed to hold the parliamentary archives. [the rules for architects who had entered the competition to design a new palace to replace the one largely burned down in the disastrous fire of 16th October 1834 stated that the palace should include "fireproof repositories for books and documents"]. Today there are 5.5 miles of shelving - some in specially temperature and humidity controlled rooms - holding the archives which start in 1497. It is estimated that it is now 80% full!
Details of the holdings can be accessed here.
Click here for a history of the Parliamentary Archive
There is an online virtual tour of the tower accessible here. A souvenir booklet to commemorate the 150th anniversary of the completition of the tower will be produced towards the end of 2010.