Kalmar Castle (Swedish: Kalmar slott) is a castle in the city Kalmar in the province of Småland in Sweden. History. During the twelfth century a round defensive tower was built on Kalmarsund and a harbour constructed. At the end of the thirteenth century King Magnus Ladulås had a new fortress built with a curtain wall, round corner towers and two square gatehouses surrounding the original tower. Located near the site of Kalmar's medieval harbor, it has played a crucial part in Swedish history since its initial construction as a fortified tower in the 12th century.
https://en.wikipedia.org/wiki/Kalmar_Castle