What is the name of the clock tower whose chimes lead London's New Year's Eve countdown?

Elizabeth Tower is the clock tower whose Great Bell chimes lead London's New Year's Eve countdown.

The tower stands at the north end of the Palace of Westminster and is commonly, though inaccurately, called Big Ben. Strictly speaking, Big Ben is the nickname of the Great Bell inside the tower, not the tower itself. The tower was renamed Elizabeth Tower in 2012 to mark Queen Elizabeth II's Diamond Jubilee.

London's televised midnight celebrations often combine the tower's chimes with fireworks launched around the London Eye. The clock became operational in 1859, while the present tower was completed as part of Charles Barry and Augustus Pugin's rebuilding of the Palace of Westminster. The bell's familiar hour notes have made it a global symbol of British timekeeping, although repair work has periodically limited public broadcasts and access.