Roof-top. It's on rails. Heavy but fast!
I live in London but have a flat in NYC. I needed a shed but only had a space of 7 feet by 30 inches. Need to be able to access the roof under concrete pavers if necessary. I bought a welder, taught myself to weld and built a chassis. Bought a steel shed kit and used an angle grinder to cut all the parts into material that I created a custom shed with. And Ruby was born.