Dolmen de Tri-Men-de-Castello, Dolmen in Kervignac, Brittany, France

The dolmen de Tri-Men-de-Castello is a Neolithic gallery grave in Kervignac, Morbihan, Brittany. Its rectangular chamber, 1.90 m by 1.20 m, is bounded by three orthostats and a supporting pillar, and covered by a single capstone 3 m long and 2.80 m wide. The orthostats are 1.20 to 2.55 m wide and 1.80 to 2 m high, and a fourth standing slab remains outside. The entrance passage has disappeared.

The dolmen was built during the Neolithic period, several thousand years ago, when people began using large stones to mark burial sites and gathering places. It was later listed as a protected monument to ensure its preservation.

The name Er Tri Men means "the three stones" in Breton, referring to the three upright slabs that frame the chamber. According to Le Rouzic, an orthostate and the pillar seemed to bear carved signs, but today only a small hafted axe is visible on the pillar. The dolmen was inscribed as a monument historique on 17 August 1934.

The dolmen stands outdoors among trees and low plants at Kervignac, in the Morbihan department. The ground is covered with fallen leaves, so sturdy footwear helps. Look for the small hafted axe, the only carving still visible, on the pillar; the other marks reported by Le Rouzic can no longer be made out.

Le Rouzic noted that one upright stone and the pillar seemed to bear carved signs, but today only a small hafted axe is visible on the pillar. The passage that once led into the chamber has disappeared, leaving the rectangular room open.