Like many churches in Friesland, St. Martin's Church was built on a terp, a heightened piece of land to protect whatever was on it from floods. Several churches had been standing on this spot before this one, although the terp had been at least two metres lower when the first church was built. The current church dates from the early 15th century and was named St. Martinus until the Reformation of 1580, when it was conficated for protestant use. Although it also served as a pilgrims church in memory of St. Boniface, who had been murdered nearby in the year 754.
Originally St. Martin was a one-aisled building in Gothic style. The northern side-aisle was added in the late-16th century and has round-topped windows. For the construction of this side-aisle stones were used of the abbey-church that was demolished in 1589 as a result of the Reformation, and that had been standing next to this church. The facade of the original aisle has a stepped gable, a 20th-century reconstruction of an old situation as known from old drawings. At the back, built directly against the choir, is a consistory with a facade dating from 1734.
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.