Although London has a plethora of historic and iconic locations, one of the top destinations is and has been the distinctive Tower Bridge. The Tower Bridge is also not to be confused with London Bridge, which sits nearby on the Thames, and has been replaced on numerous occasions over the last two thousand years. The Tower Bridge was designed by Horace Jones and John Wolfe Barry with two towers that were connected by two upper horizontal walkways; and at the time of its opening, it was the largest – and most sophisticated bascule bridge in the world. Construction of the bridge took eight years (1886-1984), and over 70,000 tons of concrete and 10,000 tons of steel. Since 1894, the bridge has been open to foot, vehicle, and water traffic, although the internal engines of the bridge have been replaced, and the original upper walkways have been renovated since the opening. While any pedestrian can walk across the Tower Bridge, or admire it from the nearby Tower of London, since 1982 the bridge has been a working museum as well with the “Tower Bridge Experience”; and since 2012, the Tower Bridge Experience has featured glass bottomed walkways in the upper horizontal passthroughs.