this is tadashi kawamata's work. it mixes art with architecture. i kind of like the ones that are more art (meaning there's no space to actually occupy) then the ones that deal strictly with architectonic spaces.
though this is cool architecture, similar to what i tried to do in my project for school.
this is a tree house that he did in madison square park in new york
this is not a good website.
try just googling his name.