I've expanded the ground level of the castle ruins and now have this:



I've redesigned the gates and added some arrow slits/narrow windows to the building. I've created the upper level of the fortress/mansion (not seen here). I still need to create the upper portion of the outer wall & gate. I'm also thinking of adding some rubble to the building itself. I'll probably add some terrain features as well but that will be one of the last steps I will do.