In the Middle Ages, the cost of a construction site depended mainly on the proximity of the materials. The closer, the cheaper. The monks of Villers understood this well when they chose to settle in the Thyle valley. Besides the abundance of water and wood, the site was surrounded by shale quarries, a stone which was used to build the abbey. To extract and work this rock, they called on a skilled workforce: rock cutters, stonemasons, mixers, masons, and sculptors. The construction of the abbey church took a century.