A first general plan of the castle of Guédelon was designed by the chief architect Jacques Moulin, then replaced by other general versions according to the evolution of the project. From those, each point of architecture was the subject of weekly staff meetings around a constantly refreshed database to help decision-making in the options to be chosen. This database has been increased over the years by trips and in situ surveys on other reference castles (same period and architectural canons), iconographic sources (illuminations, stained glass), and site accounts of the time as well as modern scientific sources (conference reports, theses, excavation reports, etc.). Such actions aimed at listing as much data as possible for their use in a comparative system destined to find the best architectural option for Guédelon. To these sources have been added the visitors themselves, who have sometimes contributed through their knowledge of techniques or architectural elements.