For tourists, photographers, residents, and even terrorists, this is the symbol of London. Officially called the Clock Tower, millions of people around the world know it as "Big Ben." In truth, Big Ben is the name of the bell inside the clock, not the tower. But trying to convince people of that is akin to trying to stop a train with your car: It's possible, but not worth the effort. Not a building on its own, the 320-foot Clock Tower is one of two towers flanking England's Houses of Parliament. It was built after a fire in 1834 destroyed most of the existing structure. That inferno was caused by the burning of an abacus that was used for bookkeeping. The fire got out of control and took most of the building with it. Charles Barry was the winner of a competition to design the new center of government. He went with a Renaissance style, and married it with Neo-Gothic details by Augustus Pugin, including the towers. Inside the tower is Big Ben -- a 13-ton bell that sounds the hours as time passes. There is no firm documentation on how the bell got its name. Some think it was named after boxer Ben Caunt. Others believe it was named after Sir Benjamin Hall, a rather hefty gentleman who was a commissioner in Westminster. Either way, it is the quintessential London experience to emerge from the Underground, walk along the Thames on a foggy Sunday morning and hear Big Ben toll. If you're not in London, it can still be heard frequently on the radio via the BBC World Service on AM in Europe, and satellite and shortwave elsewhere. For the frequency where you live, see the BBC World Service home page.

• 1949 - Big Ben's time falls behind by 4½ minutes when a flock of birds perches on the minute hand.
• 1962 - Big Ben sounds the New Year ten minutes late because of a buildup of heavy snow on its hands.

Photograph © Wayne Lorentz