Tower clock famous for its accuracy and for its massive bell (weighing more than 13 tones). It is housed in St.Stephen's Tower, at the northern end of the Houses of Parliament, in the London borough of Westminster. In coordination with Royal Greenwich Observatory, the clock was designed by Edmund Beckett Denison and built by E.J.Dent and, later, Frederick Dent. The name of the clock is said by some hictoricans to stand for Sir Benjamin Hall, the commissioner of works. At the time of the clock and bell's installation in 1859, the name applied only to the bell, but it eventually come to indicate the clock itself.