Cromlech de Kergenan, Megalithic enclosure in Île-aux-Moines, Morbihan, France.

Cromlech de Kergenan is a megalithic enclosure of 31 stones, 24 still standing, on Île-aux-Moines in the Gulf of Morbihan. The stones, 2 to 3 m high and 1 to 2 m wide, form a horseshoe about 100 m long and 75 m deep, widely open to the southeast. The tallest stone in the foreground is covered with yellow-orange lichen.

The site was first mentioned in 1827, when 24 stones were still standing. It was listed as a monument historique in 1862. A. Mauricet excavated it around 1877, when 36 stones were still visible, and René Merlet studied it in 1922, proposing a solstice alignment with the neighbouring sites of Graniol and Er-Lannic.

The site is known in Breton as Krommlec'h Kergonan, after the hamlet of Kergonan at the centre of Île-aux-Moines. Its stones stand in a horseshoe open to the southeast, and two tumuli have been identified inside the enclosure. The southern part belongs to the Conseil départemental du Morbihan and can be visited; the northern part is private land.

Parts of the site are open to visitors while other sections remain on private land and are not accessible. A leisurely walk allows you to explore the visible stones at your own pace and take in the island setting.

René Merlet suggested in 1922 that the horseshoe of stones was oriented along solstice lines and served as a sighting point toward the neighbouring megalithic sites of Graniol and Er-Lannic. Vegetation and later building work have so far prevented any check of this idea.