NASA has a server called arc.nasa.gov (password-protected) with a subdomain at settlement.arc.nasa.gov which contains a number of odd things, including an archive of artists' renderings of proposed earthling settlements in space. The proposals are basically for big round greenhouses, rotating to simulate gravity via centrifugal force - not so different than what has been proposed in a lot of science fiction in movies and on TV.
Somehow I'm comforted that there are people making plans for this kind of thing, even though it's discouraging to see how so much of the optimism of the 60s and 70s (regarding space travel as well as almost everything else) never went anywhere.