That’s really surprising news about Frankfurt.
I haven’t been there in decades, but I recall the central train station being quite close to the financial district.
Since Frankfurt is probably the fourth most important financial center in the world, I’m surprised they tolerate that.
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.