Christiansfjel Fortress was initially established by Count Wedel-Jarlsberg in 1683 as Hammersberg Skanse. A tower with a cellar powder magazine was among the first buildings at this Norwegian fortress. During Christian V's 1685 visit to Norway he visited Hammersberg skanse on June 14th. Recognizing its important location on the Swedish border, he renamed the fortress Christiansfjell and directed continued improvements. An extensive report of the visit includes illustrations of the fortress at that time.
After the Great Northern War some of the smaller border forts were determined to be more expensive than their utility justified and they were closed. On July 13, 1742 Christiansfjell Fortress was closed and the materials were moved to Kongsvinger Fortress.
References:The Château de Foix dominates the town of Foix. An important tourist site, it is known as a centre of the Cathars. Built on an older 7th-century fortification, the castle is known from 987. In 1002, it was mentioned in the will of Roger I, Count of Carcassonne, who bequeathed the fortress to his youngest child, Bernard. In effect, the family ruling over the region were installed here which allowed them to control access to the upper Ariège valley and to keep surveillance from this strategic point over the lower land, protected behind impregnable walls.
In 1034, the castle became capital of the County of Foix and played a decisive role in medieval military history. During the two following centuries, the castle was home to Counts with shining personalities who became the soul of the Occitan resistance during the crusade against the Albigensians.