Hamburg - Old Elbe Tunnel
The Old Elbe Tunnel or St. Pauli Elbe Tunnel, which opened in 1911, is a pedestrian and vehicle tunnel in Hamburg. The 426 m (1,398 ft) long tunnel was a technical sensation; 24 m (80 ft) beneath the surface, two tubes with 6 m (20 ft) diameter connect central Hamburg with the docks and shipyards on the south side of the river Elbe. This meant a big improvement for tens of thousands of workers in one of the busiest harbors in the world.