 The discovery of 15th century documents from Milan has prompted several authors to say that the keep only dates from the 15th century.Situated on the edge of a spur overlooking the valley of the River Ill, the castle lost its strategic importance in the 16th century and slowly declined.After 1659, the owners (Mazarin and his heirs) showed little interest in the structure and some external buildings were put aside (prison, keeper's house).