Inside the grounds of Nyköpingshus, Sörmlands Museum includes Kungstornet (King’s Tower), a whitewashed four-storey castle tower; Gamla Residenset, the old governor’s residence; and the neighbouring Konsthallen, with interesting art exhibitions and a collection of 19th-century boathouses. Free guided tours of Kungstornet take place in English at 2pm Tuesday, Thursday, Saturday and Sunday in summer.