Avi at Dark Roasted Blend does a great collection of images of distant worlds, but I was most interested in the visions of space stations from NASA Ames in the early 1970s; notice how everything is so green.
Clearly these designers knew something that we seem to have forgotten: If you want to build a sustainable community you need lots of trees. Cylinders, Bernal Spheres, Toroidal Colonies, all full of trees.
The occasional bridge is nice too, to remind one of home;
But clearly, the over-arching image is that of trees, clean water, modern architecture and flat roofs. (Don Davis, the artist of this and a few others, is still at it, including work for TreeHugger owner Discovery Channel). It appears that he was sensitive to this:
The 1975 NASA Ames/Stanford University Summer Study worked out the broad engineering requirements for a toroidal shaped space colony design. This painting used the design, but I refused to fill the interior with the 'shopping mall gone mad' clutter of other drawings. Again the challenge of sustaining something like a closed ecosystem was a theme I wanted to emphasize. This design became known as the 'Stanford Torus'.
Instead we built monster garages with houses attached to them and nary a tree in sight. Space looks far more attractive.