Ok, remember this is more a concept for dwarf castles and cities than anything else. I decided to add a Dam and other advanced structures, as it shows how dwarves are more technologically advanced than all the other races. There is a fictitious entrance to the mountain at the end of the fortress, so it resembles as if there were caves and that stuff there. check the screenshots attached.
Would be nice if something more similar to this could be done too:
A way to combine outside/underground in a map would be the best choice.