Ismantrop is an ancient fortress, which was used probably between years 300-500 AD. The ringfort consists of a limestone wall approximately 300 meters long and has nine gates. Inside the ringfort were 95 houses arranged in 12 blocks around a central open area with a circular building. Ismantorp is the largest and probably the oldest of the ringforts on Öland.
The first written description of Ismantorp dates back to the year 1634. Renowned botanist Carl von Linné, as well as other travellers and scholars, paid attention to the fortress. Researchers have tried to determine the fortress's age, function and history since the 19th century. Its well-preserved walls distinguish the fortress, as do the central building's unusual location on a ground elevation, the 88 visible house foundations and the nine gates.
Theories of Ismantorp's function differ widely. The fortifications suggest a defensive purpose, but its many gates make is difficult to defend. Ismantorp fortress has been compared to large Slavic castles that were both protective fortress and religious sanctuaries. Other researchers view the fortress as an integrated part of a united defence of the island of Öland.
Ismantorp, which today is surrounded by marshes in the Mittlandskogen forest, is an archaeological enigma as well as a popular place to visit.References:
Varberg Fortress was built in 1287-1300 by count Jacob Nielsen as protection against his Danish king, who had declared him an outlaw after the murder of King Eric V of Denmark. Jacob had close connections with king Eric II of Norway and as a result got substantial Norwegian assistance with the construction. The fortress, as well as half the county, became Norwegian in 1305.
King Eric's grand daughter, Ingeborg Håkansdotter, inherited the area from her father, King Haakon V of Norway. She and her husband, Eric, Duke of Södermanland, established a semi-independent state out of their Norwegian, Swedish and Danish counties until the death of Erik. They spent considerable time at the fortress. Their son, King Magnus IV of Sweden (Magnus VII of Norway), spent much time at the fortress as well.
The fortress was augmented during the late 16th and early 17th century on order by King Christian IV of Denmark. However, after the Treaty of Brömsebro in 1645 the fortress became Swedish. It was used as a military installation until 1830 and as a prison from the end of the 17th Century until 1931.
It is currently used as a museum and bed and breakfast as well as private accommodation. The moat of the fortress is said to be inhabited by a small lake monster. In August 2006, a couple of witnesses claimed to have seen the monster emerge from the dark water and devour a duck. The creature is described as brown, hairless and with a 40 cm long tail.