What goes around comes around. In the 1970s, I was fascinated by the Parkway Program in Philadelphia, set up in 1969 in just that way - a high school with no building (apart from a portable one that housed the administration). Students had classes in under-used spaces all over the city centre - art gallery, hospital, city hall. The bonus was that people who worked in those places -curators, nurses, office managers - became involved in the teaching and learning.
Did it survive? I'm not sure. In the early Eighties I gathered it was changing and settling down into fixed campuses. So many pioneering schools from that time have been bludgeoned back into line. What seems clear is that today's ICT would make a Parkway-type school a very realistic possibility. After all, there are already schools where "learning platforms" allow pupils to work at home, or in community-based "outreach centres" for some of the time.
All that's needed is imagination and a breaking down of all kinds of hang-ups, including the ones around professionalism, status and the definitions of "teacher" and "learner". Yes, there are some problems, and the project would present intriguing leadership challenges. But if all you can think of are the difficulties, and you think it's not even worth trying, remember this: the Philadelphia school district didn't agree to the Parkway Program because they were radical thinkers. On the contrary, they were conservative and cautious. What convinced them was the knowledge that the conventional high schools which they had weren't working. That's the comparison we always have to make, isn't it? Not with perfection, but with what we actually have right now.
Oh, and Parkway was very cheap, too, which helps no end.
The School Without Walls: Philadelphia's Parkway Program by John Bremer and Michael Von Moschzisker (Holt Rinehart, 1971)