Tower Bridge, London

The Tower Bridge, named after the adjacent Tower of London, is a hybrid bascule and suspension bridge that spans the River Thames in London.

The bridge spans 244 meters (800 feet) between two 65-meter (213-foot) tall pier-supported towers.

The 61-meter (200-foot) central span between the towers is divided into two bascules or leaves, each of which can be raised to an angle of 83 degrees to allow river traffic to pass over.

The bascules each weigh over 1,100 tonnes and are counterbalanced to reduce the amount of force necessary to elevate them in under five minutes.

They are elevated by massive hydraulic pumps that were originally powered by coal-fired steam engines until being replaced in 1976 by electricity and oil.

The two side-spans, each measuring 82 meters (270 feet), are suspension bridges.

Two high-level walkways run between the towers, allowing pedestrians to traverse the river even when the bridge deck is lifted.

The bridge is constructed of about 11,000 tonnes of steel and coated in Cornish granite and Portland stone.

To support the piers, more than 70,000 tonnes of concrete were poured into the riverbed.