Sverresborg or Sverre Sigurdsson's castle was a fortification built in the medieval city of Nidaros (later Trondheim). It should not be confused with Sverresborg in Bergen. Sverre Sigurdsson was king of Norway from 1184-1202. In the winter of 1182/1183 he initiated construction of Sverresborg (one of the earliest Norwegian fortresses) to provide him a more secure and more easily defended base from which to work. The location selected was easily fortified, hard to approach, and could be defended by a small force. The stone for the fortification was available only 0.6 km away in the quarry which had been used for construction the cathedral at Nidaros. Since the Archbishop of Nidaros, who had aligned with King Magnus, was in exile in England from 1180 to 1183, the stonemasons were also available. Work proceeded quickly, and Sverre, along with a detachment of his men, moved out to the castle during Lent in 1183.
The sea Battle of Fimreite in 1184 proved to be final struggle between the Birkebeins and the Heklunger; King Magnus drowned. King Sverre, after a six years of struggle, became the uncontested king of Norway. But the peace was not to last for long.
In 1188 the town of Nidaros, which had been vacated by King Sverre’s men, was attacked. His opposition stormed into the city and a bloodbath followed. The wooden fortress was torn down and the castle burnt and left in ruins. It is not known precisely when it was restored, but the Sverresaga indicates the castle had been restored by 1197. He died in Bergen on 8 March 1202. Sverresborg is last mentioned in the time of King Sverre’s paternal grandson, King Haakon Haakonson in 1263, when he allowed the walls of Sverresborg to be broken down.
In 1914 the area surrounding the ruins of King Sverre's medieval castle was appropriated for the site of the new open-air museum. The castle ruins are today the center of the Trøndelag Folk Museum. The museum had started in 1909, when a group of enthusiasts decided to gather buildings and objects characteristic of the area for purposes of preservation. The area around the fortress ruins was set aside for purposes of building a museum and the collection has grown steadily since then. Sverresborg Trøndelag Folk Museum is one of the largest cultural history museums in Norway. There are more than 60 buildings on the site now, covering a broad ethnological range.References:
Ängsö Castle was first named as "Engsev" in a royal charter by king Canute I of Sweden (r. 1167-1196), in which he stated that he had inherited the property after his father Eric IX of Sweden. Until 1272, it was owned by the Riseberga Abbey, and then taken over by Gregers Birgersson.
From 1475 until 1710, it was owned by the Sparre family. The current castle was built as a fortress by riksråd Bengt Fadersson Sparre in the 1480s. In 1522, Ängsö Castle was taken after a siege by king Gustav Vasa, since its owner, Fadersson's son Knut Bengtsson, sided with Christian II of Denmark. However, in 1538 it was given by the king to Bengtsson's daughter Hillevi Knutsdotter, who was married to Arvid Trolle.
In 1710, the castle was taken over by Carl Piper and Christina Piper. Ängsö Castle was owned by the Piper family from 1710 until 1971, and is now owned by the Westmanna foundation. The castle building itself was made into a museum in 1959 and was made a listed building in 1965. It is currently opened to visitors during the summers.
The castle is a cubical building in four stores made by stone and bricks. The lower parts is preserved from the middle ages. It was redecorated and expanded in the 1630s. The 4th storey as well as the roof is from the expansion of Carl Hårleman from 1740-41. It gained its current appearance in the 1740s.