The unusual large church was made of stone and bricks around the year 1300. The sacristy originates maybe from the earlier church. The vaults were added in the 1400s and painted with frescoes around 1470 by so-called Tierp Master. The crucifix originates from the late 1200s and limestone font from the late 1400s. The Gustavian pulpit was inaugurated in 1781.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.