St. Lawrence Church is one of Finland's most important medieval churches, first mentioned in the 14th century and built in its present stone form in the late Middle Ages. The reason to go inside is the wall and vault painting: biblical scenes from the early 1500s, bright, direct and unusually complete.
It is still an active church, so check visiting hours and avoid services unless you are attending. Give yourself time to look slowly; the paintings were made for people who learned stories by seeing them, not by reading labels.