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.
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La Hougue Bie is a Neolithic ritual site which was in use around 3500 BC. Hougue is a Jèrriais/Norman language word meaning a \'mound\' and comes from the Old Norse word haugr. The site consists of 18.6m long passage chamber covered by a 12.2m high mound. The site was first excavated in 1925 by the Société Jersiaise. Fragments of twenty vase supports were found along with the scattered remains of at least eight individuals. Gravegoods, mostly pottery, were also present. At some time in the past, the site had evidently been entered and ransacked.
In Western Europe, it is one of the largest and best preserved passage graves and the most impressive and best preserved monument of Armorican Passage Grave group. Although they are termed \'passage graves\', they were ceremonial sites, whose function was more similar to churches or cathedrals, where burials were incidental.