Thanks for showing us this Bruce! Some interesting techniques here; looks like he worked out the geometries of the 1 x 2 x 3 slopes and figured out the angle that it would take for the entire wall to be turned so those slopes are upright. Also, I've always thought those big roof slopes would make good cobblestone paths, but I couldn't figure out a way to use them because of the slopedness(if that's a word)(which I doubt).
Interestingly, the idea for this is pretty similar to the MOC I posted here a few days ago. This MOC is, of course, much more impressive and unique but great minds think alike, nevertheless!