In Western France, as in Southern France, in Ireland, sometimes in Britain and also, but more rarely, in the Iberian Peninsula, megalithic funerary chambers during the Neolithic period were covered by large burial mounds or cairns with facades several meters high. These were structured internally by dry stone walls, and sometimes also by partitions of wood or mud brick.The exhaustive excavation of one of these very large monuments, Péré tumulus C at Prissé-la-Charrière (Deux-Sèvres, France), an example preserved to the entirety of its original height, is a unique undertaking in Europe. It has provided an occasion to establish the appropriate recording methods for this type of architecture, drawing upon a synthesis of relevant experience accumulated by several generations of archaeologists who have worked on structures of this kind for more than seventy years within what is now CNRS UMR 6566. This has been combined with the contribution of new techniques developed by young researchers, on the one hand, and with the methods of “buildings archaeology” more typically applied to structures of the medieval or modern period, on the other. In presenting the methods we will first show the indispensable role of traditional observations for the development of a rigorous interpretation. Although they are often approached in a rather intuitive fashion, such observations have been formalized here, perhaps for the first time, through recording sheets. These observations have previously more often been applied to monuments that had been partially or totally levelled, or by contrast they have only been applied in a rather superficial way to large burial mounds and cairns. The exhaustive and relatively detailed study of Péré tumulus C demanded innovative approaches. New methods of 3D representation, for example, made a valuable scientific contribution. The methods used at Péré tumulus C open the way for new perspectives, including studies focused on the engineering capabilities of the Neolithic builders.