What is the unique feature of the Tower Bridge in London?

The Tower Bridge is a Grade I listed combined bascule and suspension bridge in London, built between 1886 and 1894, designed by Horace Jones, and engineered by John Wolfe Barry. The bridge crosses the River Thames close to the Tower of London. It has become a recognizable London landmark and is sometimes confused with London Bridge, about 0.5 miles (0.80 km) upstream.

The Tower Bridge is the only bridge over the Thames that can be raised for river traffic as it is a combined bascule (drawbridge) and suspension bridge. This means that the middle section of the bridge can be raised to allow river traffic to pass through. The bridge is 800 feet (240 m) in length with two towers each 213 feet (65 m) high, built on piers. The central span of 200 feet (61 m) between the towers is split into two equal bascules, which can be raised to an angle of 86 degrees to allow river traffic to pass. The two side spans are suspension bridges, each 270 feet (82 m) long.