In phase 2 I was working from the 3D render. Though maybe more complex than what I wanted I at least had an idea of what this thing was.
Using the 3d program I made slices of the model at various levels, then drew on top of them very roughly. Normally I think I would have used Illustrator to make very clean levels, but since the client wanted a sketch look I did most of the work by hand.
I did use Illustrator to set up the undercity. The Undercity was built before all of the new construction on top. I wanted a different look for it. So while everything above ground is square and haphazardly place things below ground, though in ruins is all built around a central core and radiates from it.