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:The Basilica of Santa Maria in Trastevere is one of the oldest churches of Rome. The basic floor plan and wall structure of the church date back to the 340s, and much of the structure to 1140-43. The first sanctuary was built in 221 and 227 by Pope Callixtus I and later completed by Pope Julius I.
The inscription on the episcopal throne states that this is the first church in Rome dedicated to Mary, mother of Jesus, although some claim that privilege belongs to the Basilica di Santa Maria Maggiore. A Christian house-church was founded here about 220 by Pope Saint Callixtus I (217-222) on the site of the Taberna meritoria, a refuge for retired soldiers. The area was made available for Christian use by Emperor Alexander Severus when he settled a dispute between the Christians and tavern-keepers.
The church underwent two restorations in the fifth and eighth centuries and in 1140-43 it was re-erected on its old foundations under Pope Innocent II.