These are cool. One of these gravity-driven miniature aqueducts still flows from the Sierra Nevada directly between Plaza Larga and las Pesas at one of the highest points in the Albaycin in Granada, and (I've heard) is accessible through the basements of the buildings there. It's extremely impressive that someone engineered running water to a hill that high from an even higher source miles away across deep ravines, and that it still flows.