Krickenbeck moated castle is one of the oldest on the lower Rhine. Its history dates back to the year 1104, when the castle was first mentioned. It is unclear why the old castle, which was certainly inhabited by Count Reginar, was abandoned or destroyed. In the mid-13th century the castle was moved to the current location. At the end of the 14th century the new castle belonged to the Counts of Kleve.
Johann Friedrich II of Schesaberg converted the castle into a Baroque mansion between 1708-1721. On September 7, 1902, a fire destroyed the entire mansion. From 1903 to 1904, a three-winged castle was built in the Neo-Renaissance style. Today Krickenbeck is a conference center.
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.