Wow, this is lookin' awesome! Keep up the good work!
I'd like to say, and maybe I'm jumping the gun, is that even if they weren't using masonry on grand scales, the fortifications might begin to fill out some, especially around the rivers. I mean, given the chance, they almost assuredly would tax ships passing through.
Like I said though, I don't know, it might be too earlier in their development for that!
either way, great job!