Built in Queen Victoria's rein, beneath each of the four clock faces is a carved Latin inscription - "Domine salvam fac Reginam nostrum Victoriam primam" which means "O Lord, save our Queen Victoria the First." It's a striking piece of Victorian engineering as Big Ben is completely clockwork, which is incredible given in this technological age you're lucky to buy a washing machine that lasts a year.
So long may Victorian engineering prevail, leaving Big Ben counting and marking the hours for many more years. As it is a wonderful sight to see and hear, one that always leaves me in awe.
For those interested behind the scenes videos can been seen on Parliaments YouTube channel.