Back in the 1970s, NASA was creating seriously trippy images of lush, green human habitats crammed inside tubes in space. Farms and happy townsfolk stretch upwards and even wrap over your head, like an M.C. Escher vista. More weirdness below.

We've paid tribute to NASA's concept art before, but The Urban Times has dug up a treasure trove of insane colony art, much of it by painter extraordinaire Don Davis. Check out more of our favorites below, and there's tons more at the links. [NASA via The Urban Times]