Because they could: Patents for unworkable devices. Why not patents for unworkable architecture?
Speaking of which: during an excavation in London, a team from the Museum of London uncovered part of a hydrologic machine that they then actually built using new parts. I’m reminded here of the (otherwise terrible) Stephen King novel, *The Tommyknockers*, in which a woman finds a small piece of metal in her backyard woods; while kicking away the dirt she realizes it is merely the outer edge of an alien spacecraft that crashed there hundreds of thousands of years before… The book rapidly goes downhill from there.