A more modest, but no less idealistic, example is Arcosanti north of Phoenix. I visited it in the late '80s when it was just getting started. There was not a lot then, but at least work continues. Paolo Soleri's visions were much more ambitious. https://en.wikipedia.org/wiki/Arcosantihttps://en.wikipedia.org/wiki/Paolo_Soleri
I was there only part of a day. Had a day off in Phoenix, and a colleague and I drove to Flagstaff via Arcosanti and Sedona. Discussion on that thread gives a lot of information about what has happened since. The book I bought in their store had a lot of ideas about huge cities built as monolithic structures, unlike what is on the ground now.
