100 Markkaa Suomenlinna Fortress

Suomenlinna — built by Sweden beginning in 1748 as Sveaborg, surrendered to Russia in 1808 without a shot fired, and transferred to Finnish administration in 1918 — was designated a UNESCO World Heritage Site in 1991, which directly prompted this commemorative issue seven years later. The Finnish name, meaning "Castle of Finland," was adopted only in 1918 as a deliberate act of renaming following independence.