Big Ben, London
Renamed Elizabeth Tower in honor or the Queen of England's Diamond Jubilee, the most well-known of all clock towers is still generally referred to by its long-standing nickname, Big Ben. The granite tower, the classical Roman-numeral clock face, and the giant bell were unveiled in 1859. Originally, it was the bell that carried the nickname Big Ben because of its impressive size and the volume with which it rang out the hours. Today, most people think of the entire structure as Big Ben. Anyone can see the exterior of the famous tower, but only UK residents can visit the interior of the bell tower (as part of a tour of the connecting parliament buildings).