If you like this concept read: Strength of Stones by Greg Bear Up Jim River by Michael Flynn City on Fire by Walter Jon Williamshttps://twitter.com/drethelin/status/1015379239145824258 …
Only the first is EXACTLY the concept you mentioned. Up Jim River (and the whole series - that may or may not be # 1 ) is set when tech self sustains and we have no idea how it or science works. City on Fire has druids who channel mana that is created by urbanized spaces.