The world's most famous clock

 Big Ben

Big Ben, London. Probably the world's most famous clock, Big Ben is instantly recognisable and a symbol of Britain to the world. A UNESCO World Heritage site since 1987, it was completed in its distinctive neo-Gothic style in 1859

Big Ben is the nickname for the Great Bell of the striking clock at the north end of the Palace of Westminster; the name is frequently extended to refer to both the clock and the clock tower.

The tower housing Big Ben 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 tower was designed by Augustus Pugin in a neo-Gothic style. When completed in 1859, its clock was the largest and most accurate four-faced striking and chiming clock in the world. ... Big Ben is the largest of the tower's five bells and weighs 13.5 long tons (13.7 tonnes; 15.1 short tons).

All bells, we believe, are christened before they begin to toll,” the newspaper reported as the initial bell arrived at Parliament, “and on this occasion it is proposed to call our king of bells 'Big Ben' in honour of Sir Benjamin Hall, the president of the board of works, during whose tenure of office it was cast.”

Big Ben's clock is powered by a double three-legged gravity escapement designed by Edmund Beckett Denison in 1851, which imparted unprecedented accuracy. Essentially, this invention prevents the large hands of the clock from being vulnerable to external influences, such as birds or gusts of wind, that might otherwise interfere with the swing of the clock's pendulum.