My God, that scenario is freaking perfect. Wouldn't you have, by chance, any examples on how to draw the walls like that? Assuming you didn't just make everything manually... because that would require the patience of a saint.
Well, if you mean the brick patterns, there's not really much to it. You just do it flat on photoshop, or some other image editing program, then transform. Of course, you need the area laid out before then.