The Ring Of Brodgar Stone Circle And Henge, which is part of The Heart of Neolithic Orkney World Heritage Site, is a spectacular stone circle. The ring is surrounded by a large circular ditch or henge. The truly circular layout of the ring is an unusual attribute that singles it out as one of the largest and finest stone circles in the British Isles. The Ring of Brodgar (alternative spelling Brogar) comprises a massive ceremonial enclosure and stone circle probably dating from between 2500 and 2000 BC. Around it are at least 13 prehistoric burial mounds and a stone setting (2500-1500 BC). The erecting of the stones, along with the massive rock cut ditch was an activity that required considerable manpower and organisation.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.