Ismantorp Fortress

Ismantorp Fortress is the largest and probably oldest of approximately 20 ringforts on the island of Oland, Sweden, constructed between 200-500 AD during the Migration Period. The limestone ringwall is about 300 meters long and 4 meters high with nine gates, enclosing 95 houses in 12 blocks around a central open area. Never permanently inhabited, it was used intermittently until around 650 AD. The nine gates may symbolize the nine worlds of Norse cosmology, suggesting a ceremonial or gathering function.