On Öland the time from 400 to 700 AD was a time of unrest when the local people could be attacked from the sea with short notice. To protect against these attacks they build fortified positions on strategic positions on the island so they could get inside some protective walls to hide from the enemy.
The local villagers build their houses inside the protective walls to have safety from attack. The fortress had a semicircular wall and also took advantage of some 20 meters tall cliffs in the area as part of the protection of the village.
Most of the old fortress is long gone but you can still see some remains of the old wall running through the flat landscape. Like most other attractions on the island you can just walk in and have a look from the road and then see what there is left. There really isn’t a lot left but there might be a few artifact in the ground if somebody really starts to look for them – a hundred years ago a farmer actually found a gold coin from the East Roman Empire which were coined during the rule of Justin I – he ruled between 518 and 527 so the coin must have hit the ground here after that time since it probably took a while for it to travel from Constantinople to this far north island.
If you are on the south eastern side of the island it is well worth to stop for a few minutes to have a look at this ancient fortress next to the road.