Guédelon found its models in concrete sites that were observed, measured, and photographed by members of the team. The first element of choice was the local construction techniques, in particular for the masonry and the cutting of the ferruginous sandstone. Similar models, such as the 13th-century Château de Ratilly located in Treigny, the same commune as Guédelon, and the Saracen tower of Saint-Sauveur from the 11th and 12th centuries located in the eponymous village on the road to Auxerre served as references for the overall architecture. Other castles further away, such as those of Yèvre-le-Châtel (Loiret) and Dourdan (Essonne), provided readings for the ribbed vaults for instance.