Anything in a Lagrange point would probably be good or of course the moon. If you want to see what stuff look like, and how fast it can degrade check out the TV show Life After People. It basically posits that if humans just up and disappeared as a species tomorrow what would happen. Inside of 100 years roads would have been broken up and likely completely overgrown by small vegetation and because of how flat and more or less level they are they would become paths for all kinds of wildlife.
If you want holds outs that would be good. Something akin to Fallout's Brotherhood of Steel.