The Tower Bridge is a combined bascule and suspension bridge in London and was built between 1886 and 1894. It was designed by Horace Jones and engineered by John Wolfe Barry. The bridge crosses the River Thames close to the Tower of London and is one of five London bridges owned and maintained by the Bridge House Estates, a charitable trust founded in 1282. It was constructed to give better access to the East End of London, which had expanded its commercial potential in the 19th century. The bridge was opened by Edward, Prince of Wales and Alexandra, Princess of Wales in 1894. The bridge is 240 meters in length and consists of two 65 meters bridge towers connected at the upper level by two horizontal walkways, and a central pair of bascules that can open to allow shipping. Originally hydraulically powered, the operating mechanism was converted to an electro-hydraulic system in 1972.