Baltadvaris Castle was a fortified manor house, earlier sometimes classed as a bastion castle. The masonry castle with wooden fortifications was constructed by Swedish in the 16th century, in a bend of the River Siesartis, in order to secure the road from Vilnius to Riga against attacks from Livonia. It used to be the property of the princely Giedraičiai (Giedroyć) family. The neglected castle and fortifications gradually fell into ruins. Today only the foundations remain as well as parts of the walls and of the castle gates, together with several cellars.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.