Actually there is quite the intriguing story about this;

See, the Ancient Greeks started with something called a clepsydra, which began around the year 325 BCE.
This was primarily used in court rooms but quickly replaced the sun dial. It was a greek inventor who created the first self-replenishing water clock that most clocks, including big ben, had gotten their original time from.
Galileo used the water clock to make his discoveries; if the water clock had not been invented, the advances Galileo made in science would not have been possible.