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:
Hluboká Castle (Schloss Frauenberg) is considered one of the most beautiful castles in the Czech Republic. In the second half of the 13th century, a Gothic castle was built at the site. During its history, the castle was rebuilt several times. It was first expanded during the Renaissance period, then rebuilt into a Baroque castle at the order of Adam Franz von Schwarzenberg in the beginning of the 18th century. It reached its current appearance during the 19th century, when Johann Adolf II von Schwarzenberg ordered the reconstruction of the castle in the romantic style of England's Windsor Castle.
The Schwarzenbergs lived in Hluboká until the end of 1939, when the last owner (Adolph Schwarzenberg) emigrated overseas to escape from the Nazis. The Schwarzenbergs lost all of their Czech property through a special legislative Act, the Lex Schwarzenberg, in 1947.
The original royal castle of Přemysl Otakar II from the second half of the 13th century was rebuilt at the end of the 16th century by the Lords of Hradec. It received its present appearance under Count Jan Adam of Schwarzenberg. According to the English Windsor example, architects Franz Beer and F. Deworetzky built a Romantic Neo-Gothic chateau, surrounded by a 1.9 square kilometres English park here in the years 1841 to 1871. In 1940, the castle was seized from the last owner, Adolph Schwarzenberg by the Gestapo and confiscated by the government of Czechoslovakia after the end of World War II. The castle is open to public. There is a winter garden and riding-hall where the Southern Bohemian gallery exhibitions have been housed since 1956.