As I went to the supermarket just now, I noticed some paths that had been formed by people walking over certain areas of grass over and over until no grass grew there any more… there was not only one path but several, close together, depending on where certain people had chosen to cross that particular bit, I suppose.
It reminded me of what I had read about a university that had been newly created; according to the story, the architect designed the campus with its buildings but designed no roads or footpaths on the campus. Instead, he simply had grass sown in between all the buildings.
After a year, the students had trodden down certain areas and created footpaths themselves; at that point, he had those paths made permanent by re-creating them with concrete or something. In this way, the architect said, the footpaths would be not those some architect thought were the most suitable for connecting the buildings, but the most useful by the "democratic vote" of the many students who had laid down the routes.