A geotransect from the Pelvoux Massif (external French Alps) to the Dora-Maira massif (internal Italian Alps), through the Monviso ophiolitic complex was investigated in the framework of a geological and geophysical imagery program of the continental crust: “Géo-France 3D Alpes”. In this paper we present and discuss a new interpretative crustal-scale cross section of the southwestern Alps by combining various geological and geophysical 2D/3D sources. The Apulian mantle (i.e. the Ivrea body) should be divided in two different rigid pieces separated by the prolongation, in depth, of the Penninic Front. These two mantle indenters drive the decoupling of the European crust. The deep crustal architecture is characterized by the stacking, beneath the high- to ultra high-pressure metamorphic nappes, of crustal slices extracted from the European lithosphere. The proposed structural model allows discussing the significance of the crustal-scale partitioning of the present-day strain pattern as well as the significance of the regional seismicity.