Could not do the top down part that I wanted to model. I had wanted to use a TG object and select the area that is path (everything but the walls) of the area you can see in the render. Then I want to just extrude those faces out to a point.
The problem was that , the TG object is just to large for my system and soft to work on in the ways that I know (fix the object problems which are many). The only other thing I can think of is to import the same map I used on the terrain into my modeler, and manually create faces to extrude. then import that back to TG as an object. The thing is that in TG the walls follow the terrain which has variation, in my modeler I don't know how to reproduce that without having the TG object in a manageable form.
Probably just giving up on this file again for a time.