Legend Elizabeth Tower

Big Ben is the nickname for the Great Bell of the clock at the north end of the Palace of Westminsterin London. The tower in which Big Ben is located is officially called the Elizabeth Tower; originally just the Clock Tower, it was renamed in 2012 for the Diamond Jubilee of Elizabeth II.
Tourists and locals alike often say “Big Ben” when referring to the landmark tower at the Houses of Parliament. That's wrong. Formerly known as the Clock Tower, the structure was renamed the Elizabeth Tower in 2012, in honour of the Queen’s Diamond Jubilee in 2012. It is the bell within that is correctly referred to as Big Ben.

It is believed Big Ben was named after Sir Benjamin Hall, First Commissioner for Works, whose name is inscribed on the bell. Others attest that the bell was named after Ben Caunt, a champion heavyweight boxer. Big Ben chimes every 15 minutes and the sound can be heard for a radius of up to 5 miles.
A great sense of ceremony surrounded its arrival in London. It was brought down the Thames by barge and then taken across Westminster Bridge by a carriage drawn by 16 white horses.

The clock mechanism itself was designed by Edmund Beckett Denison, who was not actually a clockmaker, but a lawyer. Edward Dent had started the initial design, but Denison ended up making multiple modifications to it, so many that he is actually credited as the chief designer. Plus, in a move that would make other attorneys scratch their heads, Denison chose not to patent his modifications, meaning that any clock designer would be free to use them.