Bårby Borg was an ancient hill fortification. It was built in two periods, first in the age of migrations and later in the Middle Ages. Bårby Borg is the only hill fort in Öland where a natural steep scarp was used as part of the fortification. The other sides were protected by stone wall. The diameter was approximately 150 meters. Archaeologists have found a gold coin from the ruins made in Byzantine Empire in the 6th century AD.
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.