In 1994, excavations on the plateau east of the Tourbillon Castle revealed a Neolithic dwelling dated to the fifth millennium BC. Other discoveries, such as dry stone walls, prove that the castle site was used during the prehistoric period. In the nineteenth century, historians claimed that a Roman tower occupied the top of Tourbillon Hill before the construction of the castle. However, historians have never been able to prove the existence of this tower; the ruins that are supposed to be the foundations of the tower actually date back to the construction of the castle chapel in the Middle Ages.