The so-called Piasts' Castle in Gliwice dates back to the mid-14th century. It consists of a tower from 1322, which was originally part of the city walls, and an adjoining building which was probably an armory. Modifications were carried out in the 15th century, between 1558-61 it became the residence of Friedrich von Zettritz. Later it was an armory, a jail, a magazine and since 1945 a museum. Between 1956-59 it was thoroughly rebuilt and partially reconstructed. Since that time it is claimed to be a Piast castle, although no sourced evidence backs this claim. Since 1959 the castle has been part of the Gliwice Museum.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.