In view of its situation on a small Baltic peninsula, Kalmar Castle has repeatedly played an important role in Swedish history. One of those occasions was in 1397, when it was the venue for the formation of the Kalmar Union, which brought together the kingdoms of Denmark, Norway, and Sweden. In the 16th century, Gustav Vasa (1496–1560), from 1521 until 1523 Protector of the Realm, and subsequently King of Sweden, stayed in the castle after his flight out of Danish captivity, and in the ensuing years, he and his sons extended it considerably. Today, the complex is one of the best-preserved Renaissance castles in Northern Europe.
Schloss Kalmar, colour photograph, 2011, photograph: Martin Grädler; source: Wikimedia Commons, https://commons.wikimedia.org/wiki/File:Kalmar_Slott_Aug2011.jpg, Creative Commons Attribution–ShareAlike 3.0 Unported (CC BY-SA 3.0), https://creativecommons.org/licenses/by-sa/3.0/deed.de.