If you walk out of the train station...ten steps out....to around five minutes out walking...that’s the area to avoid after dark. Beyond that...about another ten minutes walking is the upscale area (German version of Wall Street). Night and day.
For about ten years, mid-80s to mid-90s....in the subway area just in front of the train-station...drugs openly sold, heron shot on the spot, etc. Train station ended up hiring private security and chasing them out....whole station is clean and safe now. But the zone outside of the place is only relatively safe in daylight hours. City parks still stay clean....only because of continuous cop presence.
At one point Switzerland actually gave free heroin and methadone to addicts.
They had to register and have a medical exam first, then, they were issued a free dose, given a one-time-use sterile syringe, and had to shoot up inside the clinic.