Big Ben's chimes mark midnight during London's New Year's Eve fireworks. More precisely, Big Ben is the nickname for the Great Bell inside the Elizabeth Tower at the Palace of Westminster.
At midnight, the bell's familiar strikes signal the arrival of the new year, while fireworks are launched around the River Thames. The display is centered near the South Bank and Victoria Embankment, with the London Eye forming one of its most recognizable visual backdrops.
A common mix-up is calling the whole tower Big Ben. The tower was renamed the Elizabeth Tower in 2012, in honor of Queen Elizabeth II's Diamond Jubilee; Big Ben properly refers to the largest bell, though everyday speech often uses the name for the tower and clock together.
London's organized public fireworks began for the arrival of 2000 and later became a regular annual event. The chimes are therefore part of a modern city celebration, not a separate clock at Tower Bridge or another landmark.