The Kalmar Union was a personal union in Scandinavia, agreed at Kalmar in Sweden as designed by widowed Queen Margaret of Norway and Sweden. From 1397 to 1523, it joined under a single monarch the three kingdoms of Denmark, Sweden, and Norway, together with Norway's overseas colonies.

Kalmar is a city in the southeast of Sweden, situated by the Baltic Sea. It had 41.388 inhabitants in 2020 and is the seat of Kalmar Municipality. It is also the capital of Kalmar County, which comprises 12 municipalities with a total of 236,399 inhabitants (2015). Kalmar is the third largest urban area in the province and cultural region of Småland.