Tower Bridge
Despite its medieval appearance, London's most famous bridge was actually built at the tail end of the Victorian era in the then-popular neo-Gothic style, first opening to traffic in 1894. With a latticed steel construction clad in Portland stone, the bridge is known for its enormous bascules—the 1,000-ton "arms" that open to allow ships taller than its normal 28-foot clearance to glide beneath. The steam-powered bascules were a marvel of Victorian engineering when they were created (you can still visit the Engine Rooms, now with explanatory films and interactive displays), and required 80 people to raise and lower. Initially, heavy river traffic meant this happened 20 to 30 times a day, but it's now reduced to a number of days per month, with greater frequency depending on the time of year (see the bridge's website for a schedule).
The family-friendly Tower Bridge Exhibition includes the ground-level Engine Room, displays in the North Tower documenting the bridge's history, access to the east and west walkways that run alongside the road between the turrets and provide views over the river and city, and for those untroubled by vertigo, a transparent walkway 138 feet up between the towers that lets you look down on the traffic or, if the bascules are raised, the ships below.
