Here it is! A 3d color version of Escher's Tetrahedral Planetoid, complete with plants. I'm sure there are a few things I missed, but it's very nearly all there. I'm working on spiffing up the parts that you can't see. Should have some other views pretty soon.
Seeing this in its "final" state is very rewarding. This has been an off-and-on project (and mostly off) for over three years. I'm in the planning stages of writing a computer program (a script really) that will create this kind of radial tiered city automagically. Should be a challenge.