It was built at the end of the 13th century under the direction of Bishop Boniface de Challant. Of a defensive nature and perched on the top of a steep, rocky hill, it served as the residence of the bishops of Sion. The Tourbillon Castle was badly damaged by the conflicts between the bishops and the people of Valais. It was burnt down in 1417 during the Raron affair, a war between the people of Sion and the Raron family. It was rebuilt by Bishop William III of Raron some thirty years later. In 1788 it was completely destroyed by another fire. The stones of the castle were used for some time for construction in the region before the ruins were reinforced in the 19th century to make it a historical monument. The castle is a Swiss heritage site of national significance.