The city of Helsinki, Finland (belonging to Sweden at the time) is founded by King Gustav I of Sweden.

Helsinki is the capital and most populous city in Finland. It is on the shore of the Gulf of Finland and is the seat of southern Finland's Uusimaa region. About 690,000 people live in the municipality, with 1.3 million in the capital region and 1.6 million in the metropolitan area. As the most populous urban area in Finland, it is the country's most significant centre for politics, education, finance, culture, and research. Helsinki is 80 kilometres (50 mi) north of Tallinn, Estonia, 400 kilometres (250 mi) east of Stockholm, Sweden, and 300 kilometres (190 mi) west of Saint Petersburg, Russia.

Gustav Eriksson Vasa, also known as Gustav I, was King of Sweden from 1523 until his death in 1560. He was previously self-recognised Protector of the Realm (Riksföreståndare) from 1521, during the ongoing Swedish War of Liberation against King Christian II of Denmark, Norway and Sweden. Gustav rose to lead the Swedish War of Liberation following the Stockholm Bloodbath, where his father was executed. Gustav's election as king on 6 June 1523 and his triumphant entry into Stockholm eleven days later marked Sweden's final secession from the Kalmar Union.