Low/Raise Terrain To Top of Wall

I am making a Dwarvish level right now and the only way to make it look like it is carved out of rock is to build the walls and then raise the terrain all the way up. This gives it the cleanest look when I am doing the top-down for D&D. The biggest issue I have is that I would like the terrain to only go to the top of the walls for pictures and other aspects.