Steel general is right about the shadows. Drop shadows doesn't work when they're that far away, it just seems like it's a roof floating above the ground.
The corners of the shadows should be attatched to the corners of the buildings.
Shadows on that scale are a pain, and it's often easier to hand paint them, there's some tuts about 3d shadows out there.

I think you've gone a bit overboard with the fortification with the walled in roads, but you maybe have a reason.
Otherwise you should have some courtyards and gatehouses around the entrances to each district.
I could give you a long post about the principles of medieval fortification if you like, I'm not an expert I do know something about it.
On the other hand, they could be rich enough to build it like this, but it doesn't seem very safe imo.