Lake Köyliö and its surroundings are classified as one of the National landscapes of Finland.

[3] Köyliönjärvi is the home of the first documented historical event in Finland as Saint Henry was allegedly murdered by peasant called Lalli on the ice of the lake in 1156.

Kirkkokari Island is located near the murder site.

The story of Henry's death on the lake is the subject of the song "Köyliönjärven jäällä", by Finnish metal band Moonsorrow.

This Western Finland location article is a stub.