Alter Elbtunnel

The Alter Elbtunnel of 1911 is Hamburg's subterranean industrial monument and one of the loveliest accidental viewpoints in the city. Running 426 meters under the Elbe, it once carried shipyard workers from St. Pauli to their jobs in the Steinwerder yards on the southern bank - an engineering sensation in its day: pressurised-air construction, 24 meters deep, two tubes of six meters diameter. Four enormous elevators for people and cars in the entrance buildings take visitors down, and a five- to seven-minute walk through the historic pedestrian tube delivers you to the other side. The punchline: from the southern exit at Steinwerder, you get arguably the most unusual skyline view in Hamburg - Elphi, Michel, Landungsbrücken and HafenCity lined up like a postcard against the working shipyards. On a clear late afternoon, one of the best photo spots in the city. Practicalities: free for pedestrians and cyclists at all times; cars have not been allowed since 2019 (the east tube is being refurbished, the west tube reserved for local residents). Getting there: U3/S1/S3 Landungsbrücken, then to the St. Pauli entrance. Tip: head over through the tunnel and come back on HADAG ferry 75 to Finkenwerder or 73 to Steinwerder - the cheapest harbor tour in the world for a 4 € HVV single ticket. A very rewarding 90-minute sightseeing hack.