The sewerage system of Cologne is part of the water infrastructure serving Cologne, Germany. Originally built by the Roman Empire in the 1st century, the city's sewer system was modernised in the late 19th century. Parts of the subterranean network are opened for public tours, and the unusual Chandelier Hall hosts jazz and classical music performances.
The first sewers in Cologne were built by the Romans in the 1st century, and there was little change for 1,800 years. As the population of the city was rapidly increasing throughout the 19th century, it became apparent that the existing sewerage system was unable to cope with the volume of waste that was being produced. Raw sewage was directed to the Rhine river, causing significant problems with disease and odor. English poet Samuel Taylor Coleridge wrote in 1828 that the city had "two and seventy stenches, all well defined, and several stinks!"
Wikipedia https://en.wikipedia.org/wiki/Cologne_sewerage_system
Address 19 Theodor-Heuss-Ring, Köln 50668, Germany
Coordinates 50°57'2.398" N 6°57'48.391" E