Apart from the Victoria Tower, the Palace contains two other striking towers. Over the middle of the Palace, immediately above the Central Lobby, stands the octagonal Central Tower (91.4m, 300ft). Unlike the other towers, the Central Tower has a spire, and contains the largest known octagonal Gothic vault without a central pillar.
The tower was originally designed to serve as a ventilating chimney for stale air and smoke from fireplaces. Due to its position in the centre of the building, the tower was the first to be completed, and its construction required considerable engineering skill.
At the north-eastern end of the Palace is the most famous of its towers, the Clock Tower (96.3m, 316ft), commonly known as Big Ben after its main bell. The tower also houses a large, four-faced clock designed by Augustus Pugin. Pugin’s drawings for the tower were in fact the last work he did for the Palace’s architect Charles Barry, and it is known that Barry had great difficulty in working out how to make the clock sufficiently prominent.