In order to fully investigate the technology required in the past, the project is using only period construction techniques, tools, and costumes.

Jacques Moulin [fr], chief architect for the project, designed the castle according to the architectural model developed during the 12th and 13th centuries by Philip II of France.

In 1979, French entrepreneur Michel Guyot purchased the ruins of the Château de Saint-Fargeau and began restoring it with profits raised on-site.

[2] In late 1995, a study by Guyot's staff revealed the medieval foundations beneath the current, brick ruins, complete with a hypothesized plan of the original castle.

[2] A former sandstone quarry was chosen as the site of Guédelon Castle because of its relative elevation and abundance of local natural resources, which would have been expensive to transport in the Middle Ages.