St Stephen's Tower, London
St Stephen's Tower, also called Central Tower, is a 91 metre (300ft) tower in the Palace of Westminster. This makes it the shortest of the three main towers of the Palace. Unlike the other towers, St Stephen's Tower has a spire. The Tower is directly above the Central Lobby, ans is octagonal in shape.
The original purpose of St Stephen's Tower was as a high-level air intake. Between Westminster Hall and the Old Palace Yard, there is a small tower that contains the main entrance to the House of Common. It is known as St Stephen's entrance.