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:Visby Cathedral (also known as St. Mary’s Church) is the only survived medieval church in Visby. It was originally built for German merchants and inaugurated in 1225. Around the year 1350 the church was enlarged and converted into a basilica. The two-storey magazine was also added then above the nave as a warehouse for merchants.
Following the Reformation, the church was transformed into a parish church for the town of Visby. All other churches were abandoned. Shortly after the Reformation, in 1572, Gotland was made into its own Diocese, and the church designated its cathedral.
There is not much left of the original interior. The font is made of local red marble in the 13th century. The pulpit was made in Lübeck in 1684. There are 400 graves under the church floor.