In the 12th and 13th century, Näs (or Visingö) Castle on the southern end of Visingsö was the residence for the fragile Swedish monarchy. It was built probably by Sverker I of Sweden (died in 1156) or his son Charles VII of Sweden (Karl Sverkersson). Näs was thereby the oldest Royal castle in Sweden. It was a residence 5-6 kings before in 1318 Birger I (Birger Magnusson) pawned it to Danish. The castle was probably demolished soon after.
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.