Japanese apartments...

http://www.thecoolhunter.net/images/stories/_2006/design/japartment.jpg

Arakawa(the designer) believes that comfort makes you grow old quick, and that residents, in particular elderly ones, need to be kept on their toes by having their interiors physically challenge them. Lopsided floors force the resident to maintain a good sense of balance , strangely located light switches insist we feel around for the light, whilst small veranda doors will ask you to crawl and bend to enter.

Feel free to post your own cool buildings.