International audienceThis article presents the results of six years of excavation at Tumulus C in the megalithic cemetery of Prissé-la-Charrière (Deux- Sèvres). This is a trapezoidal mound 115 metres long, 30 metres wide and 4 metres high, that was constructed in several stages. The earliest stage that has so far been documented consists of a small funerary monument measuring 7.2 metres east-west and 8.8 metres wide. It was built largely of earth, and contained a cist open on one side and enclosed within a circular dry-stone mass. At a later stage, the entrance to the cist was blocked and the monument extended towards the east to form a long mound 23 metres in length. This mound was entirely surrounded by an encircling ditch. Later still, ...