Ivano castle history dates probably to the late 6th century AD, when Longobards built a fortifications against Franks and Alemans. Later it was extended agains Hungarian invasions. The first recorded document about the castle dates back to 1187 and there is a mention of the Lord of Ivano.
The Castle displays a mixture of architectural styles: the medieval walls, the Renaissance residence and the Benedictine lodge. From the watch tower you come to a moat and a large gate, followed by the outer courtyard with a fountain and an historical acacia tree from the 16th century. Next are the large hall of the old barn and the 17th century chapel. As you go on, you reach the inner courtyard, with two buildings linked by galleries.
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.