The traces of the Ice Age in the ruggedly beautiful lake landscape.

At Koikkalanmylly in Juva, on the shore of Lake Ruokojärvi, are the Kirkkokivet, a group of large glacial erratic boulders. Rising majestically along the desolate shores of the wilderness-like Lake Ruokojärvi, the Kirkkokivet present a striking sight, with the largest boulder reaching over ten meters in height.

The Kirkkokivet are also mentioned in the book Suomen luonnon pyhät paikat (Sacred Places of Nature in Finland), from which the following text is quoted:

"According to stories, this place was the church of the old-time wilderness men, where sacrifices were made for a good hunt and to give thanks for it. Voitto Viinanen considers it to be the 'deer church' for the wilderness men of the Lake Ladoga region, Häme, Karelia, and later the Savonians before the Great Wrath (Isoviha), marking the end of the large-scale deer hunting season. Later, the Kirkkokivet became a forest church for the local fishermen and hunters, where they worshipped the spirits of the forest and the lake. It was also a location for assembly and a wartime hiding place where priests held church services and performed baptisms and weddings. It is said that there was a very old boat landing and a purnu, a dug-out meat and fish storage pit."

The forest road leading to the Kirkkokivet can be accessed from the Koikkalantie junction at address Koikkalantie 768.

The site is protected under the Nature Conservation Act.