Nitra castle was built in the 11th century on the place of an earlier fort. The core of the castle is St. Emmeram's Cathedral with the Bishop's residence, with several different parts. The oldest surviving part is the Romanesque Church of St. Emmeram from the 11th century. The other two parts of the cathedral are the originally Gothic Upper Church from the 14th century, and the Lower Church from the 17th century. Vazil´s Tower is another remaining part of the medieval fortification. According to a legend, Vazil, king Stephen´s nephew, was imprisoned in a dungeon supposed to be in the Tower´s underground.
The originally Gothic Bishop's Palace got its present Late Baroque appearance in the 18th century. There are also surviving parts of the castle fortifications, the majority of which were created in the 16th and 17th centuries and smaller part from the Middle Ages. The church is currently being remodeled.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.