The tinest coolest houses ever! 
These diminutive abodes are amazing. Some you can buy and have shipped, or you can buy the plans for any of them.  At least two, and maybe a third, could easily be in Chicago’s under 100 sq. foot ordinance for not requiring a building permit (though electricity might be a problem).

Very interesting, and great example of a tiny footprint, literally.

Houses | Tumbleweed Tiny House Company