Kasteel Radboud is one of a number of castles in North Holland, the building was commissioned by Floris V. The exact date of building is not known but the castle was completed before the St. Lucia's Flood of 13 December 1287. On 24 June 1517 the castle saved some of the Medemblik townsfolk from the raids of Grutte Pier and his Arumer Zwarte Hoop (band of marauding pirates).
On 12 August 1588 the castle surrendered to Diederik Sonoy and the Geuzen. The defensive function of the castle was reduced with the building of walls around the city of Medemblik in 1572 and due to both dismantling and lack of maintenance there was attrition of the castle buildings.
In 1889 the control of the property was returned to the state. Restorations were done by the State architect J. van Lokhorst with advice from R.J.H. Cuypers and the castle was used for the district court of justice until 1934. In 1931 a cannery near the castle burnt down exposing the foundations of a tower on the north west of the site and during 1936 the castle-moat was dug again.
From 1964 to 1965 further restorations were done with a more historical and architectural correctness and some of the previous renovations were removed.References:
Kristiansten Fortress was built to protect the city against attack from the east. Construction was finished in 1685. General Johan Caspar von Cicignon, who was chief inspector of kuks fortifications, was responsible for the new town plan of Trondheim after the great fire of 18 April 1681. He also made the plans for the construction of Kristiansten Fortress.
The fortress was built during the period from 1682 to 1684 and strengthened to a complete defence fortification in 1691 by building an advanced post Kristiandsands bastion in the east and in 1695 with the now vanished Møllenberg skanse by the river Nidelven. These fortifications were encircled by a continuous palisade and thereby connected to the fortified city. In 1750 the fortress was modernized with new bastions and casemates to protect against mortar artillery.