There's plenty of room left to build in the world's major cities; we just have to be MacGyver about it. Because when one group of architects looked at an alley, they saw the perfect lot for a five-story building that's less then eight feet wide.
Built on a steel frame, this home office took only a few weeks to construct. It's particularly eco-friendly (as it can piggyback off heat from adjacent buildings otherwise lost to the alley's air), and while each level is absurdly small, the floor to ceiling windows do wonders to cut through the jail syndrome (evoking more of a caged hamster vibe). Really though, it all makes sense...other than the bathtub on the roof.