The St. Pauli Elbtunnel — known locally as the Alter Elbtunnel — is a remarkable piece of Edwardian engineering and one of Hamburg's most-loved curiosities. Two parallel cast-iron tubes run 24 metres below the river bed, connecting St. Pauli with the southern bank at Steinwerder. To reach them you ride down in one of the original 1911 lifts; cars and bicycles share the cage with the pedestrians.
The tunnel itself is tiled in white and lit by warm yellow lamps, with ceramic friezes on the walls showing fish, harbour scenes and turn-of-the-century life. Pedestrians and cyclists can use it 24 hours a day; cars only during specific weekday windows, and never on weekends. The southern entrance opens onto a riverside path with one of the best views of the Hamburg skyline.