Built in 1902 to allow south London’s dockworkers easier access to the docks, the cast iron Greenwich Foot Tunnel tunnel runs under the Thames from Cutty Sark in Greenwich to the Isle of Dogs on the north side. It’s 1,214 feet (370m) in length and around 50 feet (15m) deep with spiral staircase at either end. Lifts were later added in 1904. Entrance is through two grand large glazed domes at either end, which along with the tunnel are listed structures. Along with the Woolwich Foot Tunnel, which opened in 1912, the passages were restored recently and are now used by 1.5 million people a year.