First of all - great piece of work. Good job, I love it!
But there are things I think could make it better.
1. I'm not sure about algorithms and technology behind it, but I would love it as downloadable .svg file or some other vector based file.
2. I noticed there is always a castle and always towers in walls and always castle is separated from the city and kinda outside. How about optional checkboxes for "no towers", "no castle", "no walls" or "castle in the center"? I would love it evem more ;)
I'm gonna use it in my RPG campaigns with my players.