In the 16C, the future Charles IX, then Duke of Södermanland, had a sumptuous Renaissance palace built. It was destroyed by fire in 1665 and never restored; all that remains is the Renaissance guardroom and the Kungstornet ("King's Tower"), as well as the ruins of an old keep, with its legendary dungeons in the northeastern corner of the courtyard. The former governer's residence, Gamla Residenset, dating from the 18C, gives onto the outer courtyard.