The LA3M Laboratory of Aix Marseille University (France), in cooperation with the Institute of Archaeology and Ethnography of the Armenian Academy, represented on the ground by the Regional Museum of Shirak, has carried out, from 2009 to 2016, an archaeological survey of the early Christian and medieval site of Yereruyk. The project was aimed at a multidisciplinary approach of the complex, combining armenology, history of art and architecture, building archaeology, classic archaeology, archaeological anthropology, and geo-archaeology.One of the purposes was to better understand the reasons why such a large ensemble had been established in a space now deprived, at the northwestern tip of the country. The complex includes the vestiges of several buildings, among which an early Christian basilica, a vaulted construction which served perhaps as a mausoleum, the remains of a “false rampart”, and of a series of parallel walls corresponding, at a certain period, to a dam, two underground halls, and numerous fragments of sculpted stones. A special attention was paid to the basilica and to the cemetery, where twenty-seven tombs were studied in detail. Another objective was to try to clarify the absolute and relative dating of the main buildings, as well as the function of many of them, which was still unclear. The mission also sought to specify the relationship which must have existed around the year one thousand between the religious complex and the medieval capital Ani, from which it is only some kilometers away.