Nyköping Castle

The site began as a kastal raised in the second half of the 12th century; whether it stood square or round, like the contemporary Kilakastalen, is not known. Birger Jarl is thought to have enlarged it into a larger castle. The old tower was rebuilt when it was absorbed into the works around it. In two stages during the second half of the 13th century a rectangular castle with two outer baileys went up on the site, to all appearances finished in the 1280s.

Erikskrönikan has Magnus Ladulås taking up the duchy of "sudermannaland ok nyköpungs hwss" in 1266, though the chronicle was composed only in the following century. The first documentary mention of Nyköpingshus comes in 1305, when Erik Magnusson signed a bond there.

In 1308 Ingevald Estridsson of the Hammersta family held the castle as bailiff for the dukes Eric and Valdemar. A division between the royal brothers handed it to Birger Magnusson in 1310. In December 1317 it was the setting of the Nyköping Banquet, a Christmas feast that ended horribly for Eric and Valdemar, brothers to King Birger. After the dukes' supporters took the castle, the greater part of it was pulled down, and the place stood derelict for years.

In 1365 the castle was granted in fief to the German knight Raven von Barnekow, who had it restored. Albert of Mecklenburg laid claim to it during the 1370s but appears never to have taken possession; in 1376 it passed instead to Bo Jonsson Grip, and in 1388 his executors made it over to Queen Margaret. On 20 September 1396 the Recess of Nyköping was signed here, one of the great events of the Nordic Middle Ages and a prerequisite for the formation of the Kalmar Union the following year. In 1434 the troops of Engelbrekt Engelbrektsson besieged Nyköpingshus, and the garrison surrendered it to them after a parley.

Sten Sture the Younger stormed the castle in 1516 after Sten Kristiernsson Oxenstierna declared himself ready to give it up to Christian II; the garrison capitulated after a single assault. Gustav Vasa strengthened the place for defence, and a round gun tower of his time survives. On 3 March 1538 Svante Sture the Younger was married to Märta Eriksdotter Leijonhufvud here.

At the end of the 16th century Duke Charles, later Charles IX, rebuilt the medieval castle as a Renaissance palace. Erik Sparre, taken prisoner after Charles defeated Sigismund III Vasa's forces at the Battle of Stångebro, was held in the castle until his execution at the Linköping Bloodbath. Charles IX died at the palace on 30 October 1611, and Charles X Gustav was born there on 8 November 1622. The palace burned with the rest of the town in 1665; it was never re-erected, and some of its brick went into the rebuilding of Stockholm Palace.

More of the palace burned in 1719 during the Russian ravages. A new residence, now called Gamla residenset, was afterwards built within Nyköpingshus at the request of the governor Nils Gyllenstierna. Parts of the castle stayed sound enough to serve as the county residence until the 1760s. Parts of the castle were refurbished in the 20th century, and the complex has been a governmental listed building since 25 January 1935.

The National Property Board of Sweden owns the site and Sörmland Museum operates it, with the permanent exhibits in the King's Tower and the Old Residence and a restaurant in the banquet hall and the Queen's Cellar. In October 2020 a previously unknown chamber, thought to have been a defensive room or casemate, came to light.