What is the official name of the London clock tower commonly called Big Ben?

The official name of the London clock tower commonly called Big Ben is Elizabeth Tower.

The tower stands at the north end of the Palace of Westminster in London. It was completed in 1859 as part of Charles Barry and Augustus Pugin’s Gothic Revival rebuilding of Parliament after the old Palace of Westminster was destroyed by fire in 1834.

Big Ben properly refers to the great bell inside the tower, not to the tower itself. The clock is officially the Great Clock of Westminster, and its four large dials became one of London’s most recognizable sights. The tower was renamed Elizabeth Tower in 2012 to mark Queen Elizabeth II’s Diamond Jubilee; it had previously been known as the Clock Tower.

The bell first struck in 1859, although it cracked soon afterward and was repaired. The tower underwent major conservation work from 2017, with the clock and chimes returning to regular service in 2022.