See also Art by Time Period: Medieval.
Architecture & Patrimoine: Bibliography for French architecture and architects. Site in French.
Chartres: Cathedral of Notre-Dame. Site hosted by the University of Pittsburgh.
Mapping Gothic France. Database of images, texts, charts and historical maps.
Merian Map of Paris (1615). Images on Wikipedia page.
Paradoxplace: An amateur site with many photos of French architecture. Images may be used for educational purposes with proper attribution.
Paris in the 19th Century. Maps and views from the University of Chicago Library's Map Collection.
Moteur Collections: Records and images of French architecture. Site in French.
Royaumont Abbey. Includes panoramic views and virtual reconstructions.
Turgot Map of Paris (1734-1736): Images on Wikipedia page. Highly detailed - one can zoom in to see individual buildings.