So the information you want is how the settlements historically looked like?
So you can, hopefully, make them so ingame?
Well, since you opened up the thread, why don't we start with Paris;
This little .pdf file I found reconstructs the medieval plan of the city(thought from a bit after this mods startdate, ignore the outer wall and moat);
http://paris-atlas-historique.fr/resources/$C3$A9volution+1300_1450.pdf
-still is useful for the overall layout
Though, the model for the mod should be a reconstruction of Paris before the erection of the Wall of Charles V and focus on the walls of Philip II Augustus instead(those walls being largely a 12th century thing).
Here is a 3d representation of such a 12th/13th century Paris;
Another one with greater detail(from above);
http://i.imgur.com/MlkxZg8.jpg (large image)
Inner island walls and bridges;
Reconstruction of what one of the many outer gates looked like;
The Louvre Fortress/citadel;
That is just some data leftover from one of my own "things" I did some time ago.
Hope it helps or at least gives a little push