One of the best outcrops of the European Variscan Belt is located in the Iberian Massif, mostly within the South and Southwestern part of the Iberia Peninsula. It is also one of the most and best studied section of this orogenic belt. Studies include multi seismic (normal incidence and wide angle) reflection profiles (IBERSEIS and ALCUDIA), potential field (including Magnetotelurics, Gravity) and lately regional heat flow (Curie Depth Analysis). Integration of these multi-disciplinary data and data products is carried out in this work in an attempt to unravel the nature of the main architectural features imaged within the crust and upper mantle, as well as to resolve the role played by the most outstanding crustal and intra-crustal discontinuities. These targets are addressed within the light of correlations between seismic reflection signatures, velocity anomalies (and Poisson¿s ratio) and the estimated thermal field. For example, seismic transparent zones featuring relatively high values of Poisson¿s ratio are consistent with increase in quartz (perhaps granite with high Si content). In other examples coincident high seismic velocities, high electrical conductivity and high amplitude multi-cyclic reflective patterns are consistent with layered mafic intrusions. The multi seismic reflection data reveal a crust featuring two mayor levels characterized by contrasting internal structures. The upper and the lower crust are bounded by a thin interface at mid crust depths, approximately, 14-17 km. The estimated thermal field (estimated isotherm) seems to suggest a correlation with the present brittle-to-ductile transition, regardless of this detachment being, at least, VAriscan in age. This mid crustal discontinuity most probably has acted as a localized detachment zone and its position has not changed much since the late Paleozoic. This discontinuity also marks a P-wave velocity increase, nearly continuous along the entire Iberian Massif, suggesting an orogen-scale boundary with characteristics compatible with those of the globally debated Conrad discontinuity. The geophysicals constraints on the crust-mantle boundary (Moho) are also placed and its nature and role in the orogenic evolution is also discussed.