I think mine will just be caves - maybe hiding some sort of arsenal where they aren't too close to your archives for comfort. My area is going to bear the obvious redeveloped scars of many battles with the orcs to the west

Which reminds me...

How thick do you think the city wall should be. I've seen in other threads that it should be about 20 feet wide? I'm happy with that, but I will be making quite an impressive development around the gate I need to put in my section of the wall for access between The Ward of Erahum, and the Borough of Lurking on the outside of the wall. I'm also going to bridge many of the gorges between my cliffs with bridges and viaducts, and may even have a couple of cable car systems or primitive incline trams.