In the Middle Ages, Kalmar was Sweden's southernmost harbor, since the coasts of today's southern and western Sweden were then part of Denmark. A union treaty between Sweden and Denmark-Norway was entered in Kalmar in 1397, making Queen Margaret I of Denmark the monarch of all Scandinavia, called the Kalmar Union. Sweden left this union in 1523 and counts its independence since that time.
In more recent times, Kalmar has been an industrial city with Kalmar Mekaniska Verkstad making steam engines and large machinery. Today the city has a college and a research facility for Telia. Kalmar Castle is a powerful "fist of granite" from the 16th century, Scandinavia's most well kept renaissance castle.
See also: University College of Kalmar