Sweden Gråborg

The largest of 19 prehistoric ring castles known on Öland, and one of the largest in Sweden is the Gråborg in the wooded region of the Mittlandsskogen. The elliptical ring wall with an extension of approximately 210 x 160 meters consists of loosely stacked limestone slabs. From originally about 8 to 10 meters height 4 to 7 meters still remain, at a thickness of 10 meters. Around the year 500, the castle is said to have been built.