Barnenez is a cairn mapped by Napoleon in 1807. Used partially as a quarry. That stopped in 1950. When several additional chambers were discovered

Barnenez Cairn or Barnenez Tumulus, is a remarkable megalithic monument. Located in Brittany, France. It has been referred to as “the oldest building in the world.” Though debated. It is significant. For its historical and archaeological importance. It does offer valuable insights into the prehistoric cultures of the region.

Near Plouezoc’h, on the Kernéléhen peninsula in northern Finistère. It dates to the early Neolithic, about 6800 years ago. Along with Bougon and Locmariaquer megaliths. It is one of the earliest megalithic monuments in Europe.

It is a massive stone structure that consists of a long passage tomb or cairns. It is made up of large, overlapping stone slabs and mounds of earth. The monument is divided into two main chamber sections. With long passageways leading through the mound to the chambers.

The cairn was first mapped in 1807, in the context of the Napoleonic cadaster. The first scientific recognition took place, in the context of an academic congress. At Morlaix, in 1850, when it was classified as a tumulus.
Until the 1950s, the cairn was used as a quarry for paving stones. It was halted when more chambers were discovered. And, a restoration plan was put in place.

72 m long, 25 m wide, over 8 m high; and, 13,000 to 14,000 tons of stone
Through separate entries. 11 chambers are visible. The mound is large. It has steep facades yet a stepped profile for support. Several internal walls served as stability, or for different stages of building for the structure. Much of the cairn is small blocks of stone. It is only the chambers truly megalithic in nature. For the laborers. It must have been painful work and peaceful. With the bay of Morlaix is in the distance.

The first of two stages consisted of 5 chambers
Slightly trapezoid. Its original mound was believed to be 32m x 9-13m. In the second phase. They extended. Another wing, with six further chambers was added to the west. And, the first stages mound was made wider and taller. Using more granite. They had originally begin using the dolerite stone. It’s believed 200 workers would have taken 3 months to erect stage 1 alone (yellow on cairn map). Not bad for almost 7000 years ago.

The chambers: Dolmen à couloir or “passage grave”
Large slabs of granite encompass the passage graves. Due to quarrying. Some are now exposed. Most are corbelled (like a lean too). Each of the 11 chambers are reached via long narrow passages 7-12 meters long. Beside each other. Passages also have slab built, dry stone, or both. For there walls. Enter at your own risk.

Engraved symbols occur in several chambers and passages
Depicting bows, axes. Wave symbols or snakes. There is also a repeated ‘u-shaped’ sign, and depiction of the ‘dolmen goddess’. (photo above)
Parallel to Gavrinis. Apart of one of the carved slabs even appears to be from a different structure. In broader terms. They symbols engraved on rocks appear to be apart of the cultural phenomenon described as megalithic art.

Did you know? Chambers A, C and D, in cairn 2 contained neolithic pottery, polished stone axes, flint blades and arrowheads.

Pottery shards, a copper dagger and arrowhead were found outside the monument indicate that it was reused in the Bronze Age

Today, Barnenez is open to the public. Visitors can explore its chambers and gain a sense of its historical and architectural significance. There is no quarrying. Interpretive signs and displays provide information about the site’s history and purpose. It is considered a significant heritage site in France and a testament to the engineering and architectural skills of the Neolithic people who built it. It is also an important site for understanding the evolution of cultural traditions in prehistoric Europe.

Bibliography: “The world’s 10 oldest ruins” ( The Telegraph.

Hoskin, Michael. “Orientations of Neolithic Monuments of Brittany: (1) Context” ( Journal for the History of Astronomy. 34 (4):401–420. doi:10.1177/002182860303400403 ( ISSN 0021-8286 (

“Great Cairn of Barnenez” ( (PDF)

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