Tower Bridge Facts You Probably Didn't Know Drawbridges require ropes or chains to lift up the road, however the roadways on Tower Bridge are too heavy to be opened in this manner. Instead, it is a bascule bridge, which means the roadways (bascules) swivel to open and shut the bridge like two huge seesaws. Bascule bridges were originally used as military bridges before they were adopted for use by civil engineers. These bridges could be raised into position by soldiers using a winch and pulley system, allowing troops to cross deep rivers or narrow defiles without having to dismantle the structure. In addition to its decorative features, the bridge is also famous for being the first major suspension bridge across the Thames. The design was proposed by Sir John Rennie and built between 1824 and 1831. It consists of four towers each flanked by a paneled gallery, from which pendent cables support a decking of wood beams covered in tar and gravel. The central span measures 250 feet from end to end, making it at the time one of the largest wooden structures in Europe. London Bridge is a landmark bridge over the River Thames in London, England. It has been the scene of many a battle and trade agreement but now stands as a monument to human tragedy. Built in the 11th century, it was initially an oak bridge until 1250 when it was destroyed by fire. Between then and 1666 no further bridges crossed the river.