The aim of the study presented here is to propose a new view on the chronology of early medieval buildings in Europe and on the related building modes. If several studies have proved the efficiency of this multidisciplinary process, the case of St. Irenee’s church is very representative of the contributions of such an approach. This church is one of the oldest witnesses of the Christianization in Lyon, capital city of Gauls, and of its evolution under the aegis of Burgonds. However the small number of preserved remains of its early states has shown uncertainties in the interpretation of the chronology of the building use. There are two possibilities: is it the monument described by Gregory of Tours at the end of the 6th century? Or is it the result of the Burgond building politics at around the 9th century? Lumine scence dating on architectural ceramics brought then a new approach very complementary of the historic and archaeological data, yielding new interrogations on the use and reuse of ancient material. Some evidence allowed lifting the veil on the sanctuary origins and its evolution through time. Finally, different building phases have been determined and allowed to understand the transformation of the church between its foundation and the 10th century.