While there are obvious doubts as to whether this "castle in the sky" will ever leave its concept phase, you've got to admit the idea is breath-taking. Soaring high above, it's the next-gen hydrology system for cities.
Designed for the central-Italian city of Latina by the Atelier Ramdam Architect firm, it would span 2000sq ms, with the water tower buried beneath the lush landscape and pond. Public could potentially walk up the tower and around the rooftop, making it a landmark offering beautiful views - though coursing through the tower would be the evaporation which leads to vaporisation. Then, the precipitation falls back down to earth. [Atelier Ramdam via Designboom]