According to tradition, Saint Henry was murdered by Lalli on the ice of Lake Köyliö by the Kirkkokari island in the winter of 1156.[1] Since the 13th century it was a pilgrimage site for Catholics. A small chapel was built on the island which was used until the 18th century. Foundations of the chapel are still visible.[2] In 1955 the memorial of Christianization of Finland was erected in Kirkkokari and a small altar, "Saint Henry's altar", in 1999.[1]