Furstenburg Castle was erected in the 13th century on behalf of the Bishop Conrad of Chur (1272-1282). In the 16th and 17th centuries A.D. it was however restructured according to the style of the time. The oldest part of the castle is the tower which displays walls of a three meters thick diameter.
References:The Château du Lude is one of the many great châteaux of the Loire Valley in France. Le Lude is the most northerly château of the Loire Valley and one of the last important historic castles in France, still inhabited by the same family for the last 260 years. The château is testimony to four centuries of French architecture, as a stronghold transformed into an elegant house during the Renaissance and the 18th century. The monument is located in the valley of Le Loir. Its gardens have evolved throughout the centuries.