The Olkijoki Treaty Museum introduces its visitors to the times of the Finnish War (1808–1809), as the Lassila Inn was the place where the Olkijoki Treaty that led to the truce between Russia and Sweden was signed.. In 1918, the main building of the Lassila farm was for the most part demolished and the remaining part was converted into a museum. The rooms where the Convention of Olkijoki was signed were kept as a historical memento of the Finnish War.