That is the sound of Big Ben. People from London like to call the ringing of Big Ben “bongs.” They mark the start of a new hour. Big Ben is the name of the large bell inside the clock tower above Britain’s Houses of Parliament. The tower is part of the Palace of Westminster. There are other smaller bells, too. The structure that houses Big Ben is one of the most famous sights in the country. It is called the Elizabeth Tower. Big Ben started making its bongs 158 years ago. But beginning on August 21, it will go silent for four years. The bell will ring for the last time at 12 noon.