Tower Bridge at night, originally uploaded by TwoCrabs.

This is my favorite structure in London. It's probably also the most mistaken bridge in the world. Tourists regularly refer to this structure as "London Bridge." Well, yes, it is a bridge in London. But it's not called London Bridge. This is TOWER BRIDGE.

Although it looks fairly old, it's actually pretty modern by London standards. After an 8-year construction project, Tower Bridge was officially opened on 30 June 1894 by future King Edward VII. It was built because of the need for a new bridge in East London.

Tower Bridge is a drawbridge and was originally opened for tall ships like tea Clippers returning from the Far East on their way to the now-defunct docks in the Poole of London. The old docks in this area have since been converted into luxury condos. Today, the bridge is still occasionally opened for visiting tall ships and Royal Navy vessels that often dock alongside the HMS Belfast ship & museum. For nearly 100 years, the drawbridge was operated by steam-driven engines until it was modernized in 1974. 

Pedestrians can cross the bridge on either side of the road. The towers also contain a museum. For £6, visitors can climb the north tower, walk across the two top girders and descent down the south tower.

For the record: London Bridge is a flat, ugly, nondescript modern bridge located just west of Tower Bridge. London Bridge was the original crossing over the River Thames. It was once covered with wooden houses and shops that routinely burned, hence the old nursery rhyme, "London Bridge is Falling Down."