Kalmar Castle
Founded in the 12th century, the strategically situated fortress was once called the key to Sweden. It was here that the Danish Queen Margrethe of Denmark launched the Kalmar Union, uniting the crowns of Denmark, Norway, and Sweden. Then, in the 16th century, under order of King Gustavus Vasa and two of his sons, Erik XIV and Johan III, the medieval stronghold was transformed into a Renaissance palace.