Gråborg is the largest ancient castle in Öland. It was built probably in the 6th century and enlarged through Middle Ages. According old tax reports dating back to the year 1450, Gråborg was owned by Vadstena abbey and functioned as a some kind of trade center. It was used for defence against Danish even in 1677. According to legend Gråborg was strongly associated with king Burislev Sverkersson who had grown up there with his half-sister Sofia of Minsk.
Gråborg Castle consisted of a circular wall, about 4-7 meter tall. There were three entrances and one of them was vaulted in the Middle Ages. Archaeological excavations have revealed lot of findings, which are stored today in Kalmar Museum.
There are medieval ruins of the chapel of St. Knut on the north side of castle.References:
The Peace Palace (Vredespaleis) is an administrative building and often called the seat of international law because it houses the International Court of Justice (which is the principal judicial body of the United Nations), the Permanent Court of Arbitration, the Hague Academy of International Law, and the extensive Peace Palace Library. In addition to hosting these institutions, the Palace is also a regular venue for special events in international policy and law. The Palace officially opened on 28 August 1913, and was originally built to provide a symbolic home for the Permanent Court of Arbitration, a court created to end war which was created by treaty at the 1899 Hague Peace Conference.