A geophysical survey was carried out in 2015 for the development of the patrimonial site of the Abbey of Our Lady of Bec (also called the Bec Abbey), located in Le Bec-Héllouin, Normandy, France. This survey aimed at optimizing the future accessibility programme by preserving the historical heritage of the Bec Abbey, taking into account potential underground remains. The ground penetrating radar (GPR), the electrical resistivity imaging (ERI) and the magnetic method (MM) were used to prospect the shallow surface. The GPR imaging shows longitudinal and curvated structures, drawing the classical and simplified plan of a Romanesque church basement of the eleventh century. This is the most important discovery of this survey, since the existence of this church was historically known but has remained unlocated till this geophysical survey. The ERI measurements confirm and locally complete most of the GPR results. Despite the very magnetic-noisy environment, the MM investigation is the only method detecting a longitudinal structure that can be the foundation of an ancient wall between the Saint Nicolas' tower and the church nave of the thirteenth century. Finally, authorities recently allowed in July 2017 the publication of excavations performed by archaeologists. Most of the geophysical anomalies have helped to target the archaeological investigation and the results provide a detailled interpretation in terms of depth and nature of remnants. Archaeological investigation then offers an important historical outcome of the various stages of construction and destruction of the Bec Abbey.