The Château de Lacassagne is thought to date from the latter half of the 15th century, with additions and alterations made in every century until the 19th century. It originated as an ancient salle (hall) and was altered in the 15th century with the addition of a spiral staircase and windows. A residence was added in the 17th century. On the first floor, in a room known as the Salle des Chevaliers de Malte, the painted decor was done between 1620 and 1640 for Jean Bertrand de Luppé, prior of St Gilles, and intended as a replica of the grand council hall of the Knights of St John of Malta. Among the pictures are copies of Matteo da Leccio's paintings representing the attack on Valletta by the Turks in 1565. The originals were in the council chamber of the Grandmaster's Palace in Valletta, Malta and were destroyed by Napoleon Bonaparte in 1798.
In the 19th century, a west wing was added to the main building. The castle is not open to the public.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.