[1] One of approximately 20 known ringforts located on Öland, Ismantorp was constructed during the Migration Period.

[2] The ringfort consists of a limestone wall approximately 300 meters long and has nine gates.

Inside the ringfort are 95 houses arranged in 12 blocks around a central open area with a circular building.

Ismantorp is the largest[3] and probably the oldest of the ringforts on Öland.

[2] The castle was visited by Carl Linnaeus on his trip to Öland.