The written history of Köyliö, and the whole of Finland begins with Lalli the yeoman, Kerttu, his wife, and Bishop Henry. The murder of Bishop Henry on the ice of Lake Köyliönjärvi on the 20th of January in 1156 is the first event in Finnish history to be written down so that the time, place and main characters are still known to some certainty.
According to legend, Lalli was the man of the house in a country house on the Kirkkosaari-island. In retribution for the murderous deed, the Church seized the estate and allocated it to the Bishops of Turku. After the Reformation, the estate became the Crown’s property. Nowadays the estate is private property and is a significant producer of special plants.
According to tradition, Lalli murdered the bishop at the North end of Lake Köyliönjärvi, near Kirkkokari island, which is also known as St. Henry’s island. The first church in Köyliö stood on the island and was in use till the 1420s.
A memorial stone was erected on the spot in 1955 to commemorate the arrival of Christianity in Finland. Nowadays Kirkkokari island is the only place of pilgrimage for the Roman Catholic Church in the North. A Catholic memorial mass is held on the island every year on a Sunday closest to the 18th of June and Midsummer.
The historical road between Köyliö and Nousiainen is known as St. Henry’s road. It was named after the funeral procession of Bishop Henry. The 140-kilometer hiking route has been marked with plastic ribbons.
On Midsummer Eve, Lalli and his hired men levy a voluntary bridge tax on the Polsu-Bridge that leads to Kirkkosaari island. The proceeds are then donated to charity.