The ruins of the castle of Saint-Aubin-of-Cormier point out a significant event of Breton history. Affected by the catch of Saint-Aubin, François II, Duke of Brittany, an army of 11000 men constitutes to take again the places. During the famous battle of July 28, 1488, the French troops embank their adversaries. This event announces the end of independence of Brittany which will concretize itself with the marriage Anne of Brittany and Charles VIII. Having lost its defensive interest, the castle was going to be destroyed, except the face is keep, turned towards France winner. The fortress included a whole of 10 turns including one formidable keep and formed a quadrilateral of 100 meters out of 30. There remains only the northern half of the keep and the bases of the others turns. One also finds some scraps of the main building and the wall of the vault. The external enclosure, integrated now in constructions of the borough, keeps the trace of three grosses towers in half-moon and the southern rampart which dominates the pond.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.