Nyborg Castle was first mentioned in 1193, but the town itself was not mentioned before the year 1202. There must have been wooden or half-timbered buildings inside the walls, but we have not, as yet, found traces of them. The fortress was built on a small hill. Archaeological excavations have shown that the first moat around the fortress was a dry moat. In the first half of the 1200's, a palace was built along the western ring wall of the Nyborg fortress. The most recent excavations show that a corresponding stone building was raised along the north wall and they were connected. The palace building was the finer of the two, built of bricks in two stories, and still exists in the remaining wing. There is a small, blocked-off arched window and an arched door leading to the cellar, which belong to the palace. In the preserved building, the king met with his parliament. Apparently the royal council and later the Danehof (parliament) met on the second floor.
Countless important events happened at the Danehof (Danish Parliament) gatherings in Nyborg. In 1276, King Erik Klipping succeeded in getting the nobles to acknowledge his little son, Erik Menved, as the heir to the throne. In 1282, Erik Klipping issued his coronation charter, also called Denmark's first constitution. In 1287, the same king's murderers were sentenced at Nyborg, including Chamberlain Stig, the only one of the Danehof nobles who hadn't voted for Erik Menved as Erik Klipping's successor.
During the almost 200 years that Nyborg Castle was the seat of the Danehof. The castle grew and changed in appearance. To the east, there is a large tower called Knud's Tower; now only the lower part is preserved. It was in all likelihood built in the 1300's. Around 1400 there was a building project that led to great expansion of the castle. The palace had a story added, making it 3 stories high. Shortly after that, the palace was extended to the south wall.
In the 1520's, King Frederik I was urged to make Nyborg is residence. It is unclear whether he actually did so, but there is evidence that he planned to. He had the west wing renovated, adding large, arched windows. Inside, several of the rooms were decorated with wall paintings of geometric patterns and a new ceiling construction.
In the 17th century, Nyborg was one of three major, fortified towns in Denmark, together with Fredericia and Copenhagen. Each was placed near an important body of water - in Nyborg's case, the Great Belt (Storebælt). In 1659 the city was captured by the Swedes and relieved by an expeditionary fleet sent by the Dutch, then Denmark's allies, commanded by admiral De Ruyter.
In 1867 the fortress was abolished and the town expanded beyond the ramparts. Much of the town's southern ramparts were destroyed in this process and converted into residential areas. The western and much of the northern ramparts still exist and form the scene of an annual theatre known as Nyborg Voldspil, which is Denmark's oldest outdoor theater.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.