A living laboratory for history
In a disused sandstone quarry in Burgundy, France, a team of about 40 master builders is conducting one of the world's largest and longest-running experimental archaeology projects. The goal is to build a complete 13th-century castle from scratch. The project adheres to a strict set of rules: all materials must be sourced locally, and every task must use only the tools and techniques available in the Middle Ages. Construction began on June 20, 1997, and the project is a scientific investigation into medieval engineering.
The castle's design follows the architectural principles established by King Philip II of France in the 12th and 13th centuries. The entire site operates with a fictional backstory set in the year 1228 to guide architectural and financial decisions. The imagined owner is a low-ranking nobleman, meaning the castle is functional and not excessively ornate. This narrative helps solve construction dilemmas, such as whether to install expensive glass windows (the answer was no, opting for cheaper painted parchment). Every problem, from mixing the correct lime mortar to firing roof tiles, becomes an experiment that provides new data on historical practices.
The science of medieval construction
The Guédelon construction site functions as a medieval ecosystem. Quarrymen extract sandstone blocks, some weighing up to 1,000 pounds, which are then transported by horse-drawn carts. Stonemasons shape each block by hand, a process that can take up to eight days per stone. Carpenters hew oak from the surrounding forest for beams and scaffolding, while blacksmiths forge every nail and tool on-site.
Lifting is accomplished with human-powered treadwheel cranes, often called "squirrel cages." These wooden cranes can hoist immense loads, demonstrating the effectiveness of medieval machinery. The mortar is made from a specific recipe derived from analyzing nearby 13th-century castles. Builders discovered that specific trowel marks in the mortar create a protective calcite layer, a lost technique the experiment has rediscovered. The project has progressed from laying the foundation to completing the Great Hall's roof timbers and crowning the first tower, with an estimated completion date for the main structure around 2030.