Big Ben's clock chimes are traditionally broadcast during London's New Year's Eve countdown.
Big Ben is the nickname commonly used for the Great Bell inside the Elizabeth Tower at the Palace of Westminster. Strictly speaking, the name refers to the bell, not the entire tower or clock. The tower was previously called the Clock Tower and was officially renamed Elizabeth Tower in 2012 in honor of Queen Elizabeth II's Diamond Jubilee.
The Great Bell's deep hour chime and the quarter bells are carried by a distinctive mechanism installed in the nineteenth century. Broadcast signals make the sound recognizable far beyond Westminster, including during national celebrations and New Year's programming.
The clock and bell have occasionally been silent for maintenance or exceptional events, so broadcasts are not literally uninterrupted every year. The London Eye fireworks are another major part of the capital's celebration, but they are a separate attraction from Big Ben's chimes.