The Church of St. Olaf in Sysmä was built during the first two decades of 16th century. First records of the church in Sysmä date back to the year 1398. There may have been two churches before the present one.
The north and south walls were dismantled in 1832-1835 when the church was converted into cruciform plan according to design by C.L. Engel. The belfry was built in 1845.
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.