Which is the largest and tallest tower of the Palace of Westminster in London?

The Victoria Tower is a square tower at the south-west end of the Palace of Westminster in London, adjacent to Black Rod's Garden on the west and Old Palace Yard on the east. At 98.5 metres (323 ft), it is slightly taller than the Elizabeth Tower (formerly known as the Clock Tower and popularly known as 'Big Ben') at the north end of the Palace (96.3 metres (316 ft)). At the time of its construction it was tallest square tower in the world. It was designed by Charles Barry in the Perpendicular Gothic style and was completed in 1860. It houses the Parliamentary Archives in archive conditions meeting the BS 5454 standard, on 12 floors. All 14 floors of the building were originally linked via a single wrought-iron Victorian staircase of 553 steps, of which five floors survive.

The main entrance at the base of the tower is the Sovereign's Entrance, through which the Monarch passes at the State Opening of Parliament. On top of the Victoria Tower is an iron flagstaff from which flies the Union Flag or, when the Sovereign is present in the Palace, the Royal Standard. The flag used to be flown only on days when either House of Parliament sat, but since January 2010 it has been flown every day.