Leftovers from Communist-era Poland

Me: I really like all of these green spaces in Warsaw.
Mladen, a Warsaw transplant: But do you see this path? (Gestures to a narrow dirt line running through the grass)
Me: Yes.
Mladen: You have to walk on this because the signs say it’s illegal to walk on the grass.
Me: Oh. I wondered why no one ever walked on the grass here.
Mladen: Yup.
Me: So where’s the sign?
Mladen: Oh, there’s no sign. Everyone just knows.