Palais de la Cite, Paris

 

http://projects.mcah.columbia.edu/medieval-architecture/htm/related/ma_paris_palais_cite_01.htm

France, Paris, Palais de la Cite, plan (after Mesqui): rebuilt c. 1295-1314.

Since this is the historical site for my setting, nice to have a handy reference; I don't have to design the castle myself!

Also, found a cool one in an old French book, page 6: Le Palais de la Cité à Paris, des origines à 1417. Essai topographique et archaelogique. Jean Gerout

(Which was referenced in this JSTOR article: The Doors of the Chapel and the Keys to the Palace of Louis IX

this is nice and plain and simple, from Wikipedia:

https://en.wikipedia.org/wiki/Palais_de_la_Cit%C3%A9#/media/File:Palais.des.rois.Paris.2.png 

Floor plan of the palace as it looked following the construction of Sainte-Chapelle, by Eugène Viollet-le-Duc, with Saint-Chapelle (labeled "A") near the center and the site of the later Conciergerie below it

You know what else is really cool, though? A Reconstitution 3D de la Sainte-Chapelle et du palais royal de la Cité au XIVème siècle.! 

Also, these 3d explorations of medieval Paris: 

Paris au Moyen Age en 3D à vol d'oiseau - Suivez les hirondelles

and this one, at the 5:30-mark... (mostly cool to see the development of Paris as a whole over the centuries, though. Nascimento de Paris medieval 3D