The Kalmar Castle was founded in the late 13th century by Swedish King Magnus I. It is located on an artificial island in the city of Kalmar on the Baltic Sea. The castle became famous in 1397, when the Kalmar Union was signed here - the union of Denmark, Norway, and Sweden. In 1545, the Swedish king Gustav Vasa ordered to rebuild the castle in accordance with modern requirements. Despite the improvements, it was taken by the Danes during the Kalmar War of 1611-1613. After the country's border was transferred to the south in the late 17th century, the castle lost its defensive significance and was used first as a warehouse, then as a brewery, and finally as a prison. On the next map you can see the border of Sweden in 1658 and understand the strategic importance of the castle.
Nowadays the castle houses a museum.
Virtual tour to the Kalmar castle.
Timetable and prices.
Getting there: Kalmar has an airport, where planes fly from Stockholm and Copenhagen several times a day. Bus #20 runs from the airport to the city ($5). Bus schedule from different cities to Kalmar can be found here or here. Train timetable to Kalmar is here.
Information in English about the Kalmar transport.