Some areas had, if not fully formally, dedicated areas for graffiti.
As in, "we will leave this unadorned wall, and we won't clean up the graffiti unless it's truly an eyesore, and we won't chase you for it". The wall I most recall was close to quite utilized road, so yes it was very "public facing".
The end result was that it was the one place where I would see actually impressive graffiti, with competition to make better stuff, instead of random vandal tags.
