The vast Ismantorp fortress, with the remains of 88 houses and nine mysterious gates, is deep in the woods, about 20km northeast of Ölands Djurpark. Drive north to Rälla and take a right on Högsrumsvägen; keep following this road for about 10km to reach the fortress. It’s an undisturbed fortress ruin, illustrating how the village’s tiny huts were encircled by the outer wall. The area, just south of the Ekerum–Långlöt road, can be visited at any time.
Eketorp in Southern Öland, is an imaginative reconstruction of similar remains.
A 17km hiking trail leads from Gråborg to Ismantorp fortress.