Helsinki was founded by Swedish King Gustav Vasa in 1550 as the town of Helsingfors. Gustav intended for the town to serve the purpose of consolidating trade in the southern part of Finland and providing a competitor to Reval (today: Tallinn), a nearby Hanseatic League city which dominated local trade at the time. In order to ensure the economic viability of the city, the King ordered the citizens of several other towns to relocate to Helsinki, but the order does not seem to have achieved its intended effect. The Swedish acquisition of northeastern Estonia, including Reval, at the conclusion of the Livonian War, caused the Swedish crown to lose interest in building up a competitor to Reval, and Helsingfors languished as a forgotten village for decades thereafter.
In 1640, Helsinki was moved from its original location at the mouth of the river Vantaa (in Swedish: Vanda), but the improved harbour failed to attract traders. It was fortified by the Swedish authorities, after Russia began to assert itself in the Baltic with the foundation of St. Petersburg, by Sveaborg/Viapori (today Suomenlinna) to protect the city from Russian attacks. The fortifications began in 1748.
When sovereignty over Finland was transferred from Sweden to Russia in 1809, the Russian government decided to relocate the Finnish capital from Turku (in Swedish: Åbo) - on the edge of the Baltic Sea - to Helsinki. It was believed that the relative lack of Swedish influence in Helsinki, combined with its greater closeness to St. Petersburg, would make a Finnish government headquartered there easier to control. The fortress of Sveaborg also made the place less vulnerable from overseas. The Russian authorities rebuilt the city, intending to turn it into a stylish modern capital along the lines of St. Petersburg.
During the 19th century, Helsinki became the economic and cultural center of Finland. Beginning from the late 19th century, the Finnish language became more and more dominant in the city, since the people, who moved in from the countryside mostly spoke Finnish.
In the beginning of the 20th century, the city was already predominantly Finnish-speaking, although with a large Swedish-speaking minority. Nowadays the Swedish speakers are a small minority. The population of the city grew rapidly after the relocation of the capital there, as is demonstrated by the following table.