Big Ben, by Far the World’s Most Famous Clock. Located in London, and Officially Named Saint Stephen’s Tower- This gorgeous clock is most commonly known as Big Ben. The clock inside the tower was the world’s largest when it was installed in the middle of the 19th century. The name Big Ben actually refers to the clock’s hour bell, the largest of the clock’s five bells. The other four are used as quarter bells.The clock was the largest in the world and is still the largest in Great-Britain.The tower was constructed between 1843 and 1858 as the clock tower of the Palace of Westminster. The palace is now better known as the Houses of Parliament. The clock tower rises 316ft high and consists of a 200ft high brick shaft topped by a cast iron framed spire.