Stone wall rooms

Right now if I am making a thick castle wall I just make a giant empty room. But I would like it if there were a room option where the ceiling was a stone texture. Like larger stones around the perimeter to represent the surface stones and smaller stones and mortar in the center. It would be like a cutaway of an actual stone wall. Abstract objects need to be placed one at a time (which takes too long for large walls) and they are too shiny.