Big Ben is the nickname for the Great Bell of the clock at the north end of the Palace of Westminster in London, and often extended to refer to the clock and the clock tower. The tower is officially known as Elizabeth Tower, renamed as such to celebrate the Diamond Jubilee of Elizabeth II (prior to being renamed in 2012 it was known simply as the "Clock Tower"). The tower holds the second largest four-faced chiming clock in the world (Minneapolis City Hall having the largest). The tower was completed in 1858 and had its 150th anniversary on 31 May 2009, during which celebratory events took place. The tower has become one of the most prominent symbols of the United Kingdom and is often in the establishing shot of films set in London.
The main bell, officially known as the Great Bell but better known as Big Ben, is the largest bell in the tower and part of the Great Clock of Westminster.
The original bell was a 16 ton (16.3-tonne) hour bell, cast on 6 August 1856 in Stockton-on-Tees by John Warner & Sons. The bell was possibly named in honour of Sir Benjamin Hall, and his name is inscribed on it. However, another theory for the origin of the name is that the bell may have been named after a contemporary heavyweight boxer Benjamin Caunt. It is thought that the bell was originally to be called Victoria or Royal Victoria in honour of Queen Victoria, but that an MP suggested the nickname during a Parliamentary debate; the comment is not recorded in Hansard.
Since the tower was not yet finished, the bell was mounted in New Palace Yard. The first bell was transported to the tower on a trolley drawn by sixteen horses, with crowds cheering its progress. Unfortunately, it cracked beyond repair while being tested and a replacement had to be made. The bell was recast on 10 April 1858 at the Whitechapel Bell Foundry as a 13½ ton (13.76-tonne) bell. This was pulled 200 ft (61.0 m) up to the Clock Tower’s belfry, a feat that took 18 hours. It is 7 feet 6 inches (2.29 m) tall and 9 feet (2.74 m) diameter. This new bell first chimed in July 1859; in September it too cracked under the hammer. According to the foundry's manager, George Mears, Denison had used a hammer more than twice the maximum weight specified. For three years Big Ben was taken out of commission and the hours were struck on the lowest of the quarter bells until it was repaired. To make the repair, a square piece of metal was chipped out from the rim around the crack, and the bell given an eighth of a turn so the new hammer struck in a different place. Big Ben has chimed with a slightly different tone ever since, and is still in use today with the crack unrepaired. Big Ben was the largest bell in the British Isles until "Great Paul", a 16¾ ton (17 tonne) bell currently hung in St Paul's Cathedral, was cast in 1881.
Along with the Great Bell, the belfry houses four quarter bells which play the Westminster Quarters on the quarter hours. The four quarter bells sound G?, F?, E, and B. They were cast by John Warner & Sons at their Crescent Foundry in 1857 (G?, F? and B) and 1858 (E). The Foundry was in Jewin Crescent, in what is now known as The Barbican, in the City of London.
The quarter bells play a once-repeating, 20-note sequence of rounds and four changes in the key of E major: 1–4 at quarter past, 5–12 at half past, 13–20 and 1–4 at quarter to, and 5–20 on the hour (which sounds 25 seconds before the main bell tolls the hour). Because the low bell (B) is struck twice in quick succession, there is not enough time to pull a hammer back, and it is supplied with two wrench hammers on opposite sides of the bell. The tune is that of the Cambridge Chimes, first used for the chimes of Great St Mary's church, Cambridge, and supposedly a variation, attributed to William Crotch, based on violin phrases from the air "I know that my Redeemer liveth" in Handel's Messiah. The notional words of the chime, again derived from Great St Mary's and in turn an allusion to Psalm 37:23–24, are: "All through this hour/Lord be my guide/And by Thy power/No foot shall slide". They are written on a plaque on the wall of the clock room.
One of the requirements for the clock was that the first stroke of the hour bell should be correct to within one second per day. So, at twelve o'clock, for example, it is the first of the twelve hour-bell strikes that signifies the hour (the New Year on New Year's Day at midnight).
The origin of the nickname Big Ben is the subject of some debate. The nickname was applied first to the Great Bell; it may have been named after Sir Benjamin Hall, who oversaw the installation of the Great Bell, or after boxing's English Heavyweight Champion Benjamin Caunt. Now Big Ben is often used, by extension, to refer to the clock, the tower and the bell collectively, although the nickname is not universally accepted as referring to the clock and tower. Some authors of works about the tower, clock and bell sidestep the issue by using the words Big Ben first in the title, then going on to clarify that the subject of the book is the clock and tower as well as the bell.