The bell weighs 13.8 tonnes (13 tons 10cwt 99lb), with a hammer weighing 203.2kg (4cwt), and is tuned to E. It has a delay of 5 seconds between strikes. The clock tower contains four additional bells (known as the Quarter Bells).
Big Ben is a focus of New Year celebrations in the UK, with radio and TV stations tuning to its chimes to welcome the 'official' start of the year.