It is 13 feet (4.0 m) long, weighs 660 pounds (300 kg) and beats every 2 seconds. The pendulum is installed within an enclosed windproof box sunk beneath the clock room.

This escapement provides the best separation between pendulum and clock mechanism. Construction was entrusted to clockmaker Edward John Dent after his death in 1853 his stepson Frederick Dent completed the work, in 1854. As the Tower was not complete until 1859, Denison had time to experiment: Instead of using the deadbeat escapement and remontoire as originally designed, Denison invented the double three-legged gravity escapement. The designers were the lawyer and amateur horologist Edmund Beckett Denison, and George Airy, the Astronomer Royal.

The clock's movement is famous for its reliability. Elizabeth Tower holds the largest four-faced chiming clock in the world and is the third-tallest free-standing clock tower. It celebrated its 150th anniversary on , during which celebratory events took place. The tower was completed in 1858 and has become one of the most prominent symbols of both London and England, often in the establishing shot of films set in the city.

Big Ben is the nickname for the great bell of the clock at the north end of the Palace o Westminster in London, and often extended to refer to the clock and the clock tower, officially named Elizabeth Tower, as well.

Download big ben elizabeth tower