The name Big Ben officially refers only to the 13-ton bell inside, not the tower itself.
The clock's pendulum is housed in a wind-proof enclosure and is calibrated using a stack of pre-decimal pennies to adjust the rate of timekeeping.
Each of the four clock faces is 7 metres in diameter and constructed from over 300 pieces of pot opal glass.
The Latin inscription beneath the clock faces, 'Domine Salvam Fac Reginam Nostram Victoriam Primam', translates to 'O Lord, keep safe our Queen Victoria the First'.
During the Blitz in 1941, an incendiary bomb damaged the House of Commons, but the clock continued to strike throughout the war.
The tower leans slightly to the north-west by approximately 230 millimetres due to ground movement during the construction of the Jubilee line extension.
The light at the top of the tower, known as the Ayrton Light, shines when Parliament is in session after dark.
The cast iron clock hands weigh roughly 100 kilograms for the hour hand and 165 kilograms for the minute hand.
Big Ben is the nickname for the Great Bell of the Great Clock at the north end of the Palace of Westminster in London. The tower itself is officially named the Elizabeth Tower, standing 96 metres tall. Designed by Augustus Pugin in the Neo-Gothic style, it was completed in 1859. The clock mechanism remains one of the world's most accurate timekeepers, relying on a system of weights and a pendulum adjusted by adding old pre-decimal pennies. The bell weighs approximately 13.7 tonnes and strikes every hour. It is a UNESCO World Heritage site along with the Palace of Westminster. The tower underwent a major multi-year conservation project concluded in 2022 to restore its original colour scheme and mechanical integrity.
The mid-point of Westminster Bridge looking north toward the Elizabeth Tower.
View the tower from the Westminster Bridge walkway for the most iconic perspective.
Visit during the evening when the clock faces are illuminated to see the architectural details clearly.
Check the official Parliament website for pre-booked guided tour availability, which are limited to UK residents.
Do not attempt to cross the busy multi-lane roads surrounding the base; use the designated pedestrian crossings.
The tower is not generally open to the public; tours are extremely limited and subject to strict parliamentary approval and vetting.
