Hovedøya Abbey was a Cistercian founded on 18 May 1147 by monks from Kirkstead Abbey in England on Hovedøya island, and dedicated to the Blessed Virgin Mary and Saint Edmund. A church dedicated to Edmund already stood on the island, and the monks took this over as the abbey church, modifying it to meet Cistercian requirements. The rest of the monastery follow a modified Cistercian building plan, to take into account a small local hill. The church itself is built in Romanesque style; the rest of the monastery was presumably Gothic. During the medieval period the abbey was one of the richest institutions in Norway, holding over 400 properties, including a fishery and timber yards.
Political turmoil during the succession to the throne of Denmark-Norway led to the end of the monastery. The abbot, having supported the Protestant King Christian II, possibly in a bid to gain support in the face of the coming Reformation, came into conflict with the commandant of Akershus Fortress, Mogens Gyllenstierne, who ironically had supported the Roman Catholic Prince Frederick I. In 1532 the abbot was thrown into prison for his political involvements, and the abbey was looted and then set ablaze, thus ending 400 years of monastic activity at Hovedøya. Any hope the order might have had in restoring the rich abbey was dashed 4 years later, when the Reformation swept over Denmark-Norway.
The site was later used as a quarry for stone for Akershus Castle. The remaining ruins are nevertheless among the most complete of a medieval Norwegian monastery.
References:The Gravensteen is a castle in Ghent originating from the Middle Ages. The name means 'castle of the counts' in Dutch. Arnulf I (918–965), Count of Flanders, was the first to fortify this place, building a medieval bastion on this high sand dune, naturally protected by the river Leie and its marshy banks. This bastion consisted of a central wooden building and several surrounding buildings, also in wood.
In the early 11th century, the wooden building was replaced by a stone residence, consisting of three large halls that made up three storeys, connected by a stone stairwell. The monumental stone staircase, the light openings, the fireplaces built into the walls and the latrines were signs of considerable luxury and comfort in those days. There was probably also a tower.