EXPLORED: highest position #2 (March 7, 2012)
The "Alter Elbtunnel" (Old Elbe Tunnel) in Hamburg, Germany was a rechnical sensation when it opened in 1911. The 426 m (1,398 ft) long tunnel for pedestrians and vehicles runs 24 m (80 ft) beneath the surface and consists out of two tubes with 6 m (20 ft) diameter. It connected central Hamburg with the docks and shipyards on the south side of the river Elbe. Four huge lifts on either side of the tunnel carried pedestrians, carriages and motor vehicles to the bottom. They are still in operation, though due to the limited capacity by today's standards, other bridges and tunnels have been built and taken over most of the traffic.