Linköping Castle stands immediately adjacent to the cathedral, the two buildings forming the historic core of the medieval city. The current castle is largely a 16th-century structure built on older foundations, with the characteristic round towers and thick walls of Renaissance Swedish fortification. It served as a royal residence, a bishop's palace, and a seat of regional administration across its long history.
The castle now houses the Östergötland County Museum, with collections covering the region's history from prehistoric times through the industrial period. The archaeological holdings are particularly good, including finds from Iron Age and Viking-era sites across the county. The combination of castle architecture and museum content makes it a worthwhile visit, and the courtyard is a pleasant space in summer.