An ancient wine cellar has been located on an old french castle by using the geophysical instrument Grailfinder. This old cave which is estimated from the 15th century by experts and so has an unexpected high historical value, has been located in a depth of 21 meters. Planete Detection IDS has led this professional underground research and located the entrance of this void. By presence of the first french channel TF1 they demonstrated the metal detector Grailfinder, found the cellar and finally went down with the cameramen and discovered 4 big rooms. “It was just wonderful!” so IDS.