Menhir de Guihallon, Neolithic menhir in Lamballe-Armor, France

The Menhir de Guihallon is a Neolithic standing stone located in Lamballe-Armor. The stone is made of local gabbro rock and rises to around 5 meters high while measuring roughly 3.6 meters at its widest point.

This stone was erected during the Neolithic period and ranks among the oldest human structures in Brittany. French authorities officially recognized it as a classified historical monument in 1965.

Locally the stone is called Grosse Pierre. It stands on the highest point of the former commune of Trégomar, in the middle of a rocky chaos, and it attracts followers of local neo-paganism. About 300 m to the southwest lies the Pierre Branlante de Guihalon, a 1.9-tonne rocking stone that a child can set moving.

This stone sits on elevated ground within the commune and is freely accessible from outside. Visitors can best locate it by exploring the area and asking for local directions.

About 300 metres south-west of the menhir lies the Pierre Branlante de Guihalon, a rocking stone 1.8 m long, 1.18 m wide and 1.9 m high weighing some 1.9 tonnes, resting on an elliptical slab about 3.5 m long; a child can set it moving with a light push.