The Great Clock of Westminster

Roman numerals

The Great Clock of Westminster

The Great Clock of Westminster refers to the giant clock located within the Clock Tower (officially renamed Elizabeth Tower in 2012) at the north end of the Palace of Westminster in London, England.

The nickname “Big Ben”, which is the Great Bell housed within the Clock Tower, has sometimes been used to refer to both the tower and clock.

Features and other important facts about the Great Clock of Westminster

The clock mechanism is driven by a massive pendulum and was designed to provide precise timekeeping for the parliamentary proceedings within Westminster Palace. It is renowned for its accuracy and impressive size.

The dials of the Great Clock of Westminster measure at 22.5 feet (6.9 m) in diameter, and the minute hands are 14 feet (4.3 meters) long.

The designers of Big Ben’s Clock (the Great Clock of Westminster) were English horologist Sir Edmund Beckett Denison (1816-1905) and English astronomer Sir George Biddell Airy (1801-1892).

When designing the dials of the clock, the Welsh engineer Augustus Welby Northmore Pugin is said to have been inspired by the works of famous British clockmaker Benjamin Lewis Vulliamy (1780-1854). Augustus Pugin was also the one who designed the interior of the Palace of Westminster.

The dials of the clock are made from cast iron.

At the base of each dial is the Latin inscription DOMINE SALVAM FAC REGINAM NOSTRAM VICTORIAM PRIMAM, which means “O Lord, keep safe our Queen Victoria the First”

Unlike many Roman numeral clock dials, which show the “4” position as IIII, the Great Clock faces depict “4” as IV.

Big Ben's clock designers

Designed by Sir Edmund Beckett (1816–1905) and Sir George Biddell Airy (1801-1892), the clock housed in Big Ben is famous for its accuracy and its 13-ton bell. Image: Sir Edmund Beckett (left) and Sir George Biddell Airy