One of the earliest Neolithic chambered tombs in western France, set on a hilltop in Finistère, discovered during quarrying operations in 1953–4. Excavation of the site by P. R. Giot between 1955 and 1957 showed that there were two main phases to its construction. The first monument, dating to about 4000 bc, was a rectangular stone cairn 30 m by 20 m and perhaps 4 m high, with stepped sides. Five chambers lay inside the cairn, each approached by a separate passage opening into the south side of the cairn. One of the chambers has a number of carvings on the orthostats, including three axes. The monument was extended to the southwest around 3700 bc, with the cairn being more than doubled in length and a further six chambers added.
P. R. Giot, 1970, Barnenez. Rennes: University of Rennes