Hel·sin·ki (hěl'sĭng'kē, hěl-sĭng'-) The capital and largest city of Finland, in the southern part of the country on the Gulf of Finland. Founded in 1550 by Gustavus I of Sweden, it was moved to its present site in 1640. Helsinki passed to Russia along with Finland in 1809 and became capital of Finland in 1812, retaining that status when the country proclaimed its independence in 1917. Population: 565,000.