What is Big Ben?

The Houses of Parliament and Elizabeth Tower, commonly called Big Ben, are among London's most iconic landmarks and must-see London attractions. Technically, Big Ben is the name given to the massive bell inside the clock tower, which weighs more than 13 tons (13,760 kg).  The clock tower looks spectacular at night when the four clock faces are illuminated.

Big Ben facts

• Each dial is seven metres in diameter.
• The minute hands are 4.2 metres long (14ft) and weigh about 100kg (220lbs, including counterweights).
• The numbers are approximately 60cm (23in) long.
• There are 312 pieces of glass in each clock dial.
• A special light above the clock faces is illuminated when parliament is in session.
• Big Ben's timekeeping is strictly regulated by a stack of coins placed on the huge pendulum. 
• Big Ben has rarely stopped. Even after a bomb destroyed the Commons chamber during the Second World War, the clock tower survived and Big Ben continued to strike the hours.
• The chimes of Big Ben were first broadcast by the BBC on 31 December 1923, a tradition that continues to this day.
• The latin words under the clockface read DOMINE SALVAM FAC REGINAM NOSTRAM VICTORIAM PRIMAM, which means "O Lord, keep safe our Queen Victoria the First"
• In June 2012 the House of Commons announced that the clock tower was to be renamed the Elizabeth Tower in honour of Queen Elizabeth II's Diamond Jubilee.

• Big Ben, tower clock, famous for its accuracy and for its massive bell. Strictly speaking, the name refers to only the great hour bell, which weighs 15.1 tons (13.7 metric tons), but it is commonly associated with the whole clock tower at the northern end of the Houses of Parliament, in the London borough of Westminster. The tower itself was formally known as St. Stephen’s Tower until 2012, when it was renamed Elizabeth Tower on the occasion of Elizabeth II’s Diamond Jubilee, celebrating 60 years on the British throne. The hands of the clock are 9 and 14 feet (2.7 and 4.3 metres) long, respectively, and the clock tower rises about 320 feet (97.5 metres). Originally in coordination with the Royal Greenwich Observatory, the chimes of Big Ben have been broadcast—with a few interruptions—since 1924 as a daily time signal by the British Broadcasting Corporation (BBC).

• Big Ben, London.© David Woods/Fotolia

  How to Change Big Ben's TimeDiscover how professionals change the time on London's famed Big Ben, on Saturday, March 28, 2015.© UK Parliament Education Service

  Big Ben (right) and the Houses of Parliament, London.© damn designs/Fotolia

  Big Ben: chimesListen to the chimes of Big Ben in London.© UK Parliament Education Service

  Elizabeth Tower: interiorExploring the interior of Elizabeth Tower in London.© UK Parliament Education Service

  The clock was designed by Edmund Beckett Denison (later Sir Edmund Beckett and Lord Grimthorpe) in association with Sir George Airy (then astronomer royal) and the clockmaker Edward Dent. Denison’s principal contribution was a novel gravity escapement that imparted unprecedented accuracy to the clock. In a pendulum clock an escape wheel is allowed to rotate through the pitch of one tooth for each double swing of the pendulum and to transmit an impulse to the pendulum to keep it swinging. An ideal escapement would transmit the impulse without interfering with the free swing, and the impulse should be as uniform as possible. The double three-legged gravity escapement designed by Denison for Big Ben achieves the second of these but not the first.

   

  Big Ben, London.© Digital Vision/Getty Images

  In 1852 Dent won the commission to make the great clock, but he died before completing the project, and it was subsequently finished by his son, Frederick Dent. The clock and bell were installed together in 1859. The nickname is said by some historians to stand for Sir Benjamin Hall, the commissioner of works.

   

  Big Ben: interiorExploring the interior of Big Ben in London.© UK Parliament Education Service