Greenwich Foot Tunnel crosses under the Thames between Greenwich on the south bank and Isle of Dogs on the north bank. It was opened in 1902 to allow dock workers living on the south side of the Thames to reach the docks on the north side. The tunnel is 370m long with a diameter of 3m and has spiral staircases and huge lifts at either end. Construction is predominantly cast iron rings lined with concrete and covered with glazed white (now yellow-ing!) tiles.