Linköping Castle is Sweden's oldest profane building. The oldest part, west wing, dates from the 12th century. Currently the residence of the County Governor of Östergötland, the castle has been home to governors and bishops since the 13th century. The most famous bishop to live in castle was probably Hans Brask, Sweden's last Catholic bishop.
The Linköping Bloodbath, the public execution by beheading of five Swedish nobles in the aftermath of the Battle of Stångebro, in 1600 was held in either in Linköping market square or in the castle courtyard.
In 1700 most of Linköping city burned down, but the cathedral and castle survived. The decayed castle was moved as a city prison. The restoration began In 1796 and then the castle got its classicism style appearance. In 1880 it was again renovated to the neo-Renaissance style, but restored back to the current classicism in 1930s.
The old tower of the museum features an exhibit of the history of the castle, cathedral and diocese from the 12th century to today. Unique 14th century textiles and other valuables - especially from Sweden's empire period - are on display in the treasury. You can see a big model of the castle's state apartments in the great hall.
References:Château de Niort is a medieval castle in the French town of Niort. It consists of two square towers, linked by a 15th-century building and dominates the Sèvre Niortaise valley.
The two donjons are the only remaining part of the castle. The castle was started by Henry II Plantagenet in the 12th century and completed by Richard the Lionheart. It was defended by a rectangular curtain wall and was damaged during the Wars of Religion. In the 18th century, the castle served as a prison.
The present keeps were the central point of a massive fortress. The southern keep is 28m tall, reinforced with turrets. The northern tower is slightly shorter at 23m. Both are flanked with circular turrets at the corners as well as semicircular buttresses. Each of the towers has a spiral staircase serving the upper floors. The Romanesque architecture is of a high quality with the dressed stones closely jointed.