@ebel Apparently some Dutch hackers were doing that in some places but they tend to get found and removed quite quickly as building owners don't like it (some might have tapped the 230V).
Also roof access to buildings in many areas is much more highly restricted/watched due to fear over kids doing #parkour and falling off them. Ofc if you have friends with a tall building then it can still be done (its how most Freifunk nodes work)
@ebel if you mean the Dutch "piratenboxes" it was a discussion on our Matrix for tchncs.de, unfortunately quite a while ago. They were based on Raspberry PI's with wifi. I think some (legit) ones also exist in hackerspaces.