In the heart of Burgundy, the small town of Cluny holds a secret. The abbey standing tall in the city center is a mere fragment of what the 11th-century Maior Ecclesia once was, the biggest church ever conceived at the time. A feat that was accomplished in less than 70 years.

How were the builder monks able to erect a nave larger than that of Notre-Dame de Paris? How did the choice of vaults, a clear departure from the norm of the era, allow to gain more height? What bold techniques heralding Gothic Art were picked to flood the inside with light and enhance the spiritual aspect of the abbey? How did the monks, using a complex hydraulic system, provide water to an entire community?

This investigative documentary stems from the exceptional work of an American archeologist who spent 40 years studying Cluny in order to recreate its bygone architecture. Today, thanks to incredibly realistic 3D models and interviews with the best experts, these architectural wonders are explained, as a colossal religious city is unveiled. Welcome to Cluny Abbey, the “second Rome”.