Petit Vieux Sou gallery grave, Gallery grave in Brecé, France

Allée couverte du Petit Vieux Sou is a Neolithic gallery grave set on a small plateau in Brecé, Mayenne. It consists of twenty-one upright stone blocks forming a passage around 11 meters long, with a side entrance opening into a chamber once covered by a capstone.

Built and used between roughly 2800 and 2200 BC, the tomb entered the written record around 1907 and underwent unauthorized digging during the Second World War. Later studies clarified its layout and led to its protection as a historic monument.

The name Petit Vieux Sou comes from a nearby farm. The entrance sits in the middle of the south-west long side, a layout rare in France and compared to northern European passage graves. The two corner pillars were cut back at the base to form a round porthole opening, probably closed by a matching slab.

The monument stands on a plateau edge above the Colmont valley at 157 m altitude, about 2.5 km southeast of Brecé; access is on foot. The chamber is 11 m long with a constant width and height of 1.40 m, and the side entrance lies exactly at mid-length of the long side, reached by a short 2.20 m passage.

More than one thousand objects were recovered around the monument, including polished stone axes, arrowheads, beads, and broken clay vases, even though acid soil destroyed most bone. The nearby rough stone slabs of the cairn contrast with the finer local stone used for the uprights, showing two building traditions side by side.