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:Rosenborg Palace was built in the period 1606-34 as Christian IV’s summerhouse just outside the ramparts of Copenhagen. Christian IV was very fond of the palace and often stayed at the castle when he resided in Copenhagen, and it was here that he died in 1648. After his death, the palace passed to his son King Frederik III, who together with his queen, Sophie Amalie, carried out several types of modernisation.
The last king who used the place as a residence was Frederik IV, and around 1720, Rosenborg was abandoned in favor of Frederiksborg Palace.Through the 1700s, considerable art treasures were collected at Rosenborg Castle, among other things items from the estates of deceased royalty and from Christiansborg after the fire there in 1794.
Soon the idea of a museum arose, and that was realised in 1833, which is The Royal Danish Collection’s official year of establishment.