Beneath the streets of Vienna lies another network of passages: its historic sewer system that dates back to the mid-1800s. Orson Welles ran through these subterranean tunnels in an iconic scene in the film “The Third Man,” earning them global celebrity—as far as sewers go.

This system of tunnels and underground rivers was the most complex in Europe at the time it was built, and was widely expanded after a debilitating cholera outbreak in 1830. Storm waters and sewage were channeled into a system for the first time and kept out of the Danube and its tributaries.

The sewer was further expanded throughout the 19th and 20th centuries to keep up with the city’s population growth, and despite suffering heavy bombing (along with the rest of the city) during World War II, repairs were completed by 1950.

It’s one of the most impressive sewer systems in Europe, but this underworld of Vienna is famous for a very different reason: its iconic appearance in 1949 British film The Third Man. Set in the divided, war-torn Vienna of 1947, the film, starring Orson Welles, does an excellent job portraying the issues prevalent in post-war Vienna, including the division of the city into sectors, refugees, the black market, and penicillin theft. It eventually culminates in an eerie, tense scene featuring Welles running through the sewers, brilliantly atmospheric in black-and-white and with dramatic camera angles. 

Parts of the sewers are open to the public via a guided tour only, leaving from the Karlzplatz-Girardipark. It uses the film as a theme, but the sewers are a spectacular sight in their own right, a brilliant part of city infrastructure and a historic piece of engineering well worth seeing.

Update: The sewer system is closed until May 2019.