The Penninic and Subpenninic nappe stack of the Tauern Window (TW) in the European Alps was formed by collision between Europe (Subpenninic) and the Adria margin (Austroalpine), and finally exhumed by the northward push of the Dolomites Indenter in the Miocene. In this study, we kinematically restore a cross-section along the trace of the Brenner Base Tunnel, concentrating mainly on the Subpenninic (Venediger duplex; VD). We integrate zircon fission-track data (ZFT) as a temporal constraint for the termination of viscous deformation and test different geothermal gradients (GG). P-T-t data are used to define (i) the depth of brittle-viscous transition (ca. 300°C) and (ii) pre-indenter depth. First, we displace the VD down along the Sub-Tauern ramp below the 300°C isotherm. To that time, a GG of 50°C/km prevailed. ZFT ages reveal that viscous folding of the VD terminated at ca. 17 ± 2 Ma. Unfolding of the VD, while conserving surface area, yield that the model is extended by ca. 70 km (i.e. thus equaling indenter shortening), which means that the VD was not affected by W-E extension or lateral extrusion. Reconstruction of the hanging-wall nappes (Austroalpine and Penninic nappes) above the restored VD reveals that the total pre-indenter thickness of their northern limbs was 35–50% more than it is today. We interpret this as tectonic thinning, which was mainly caused by the Brenner normal fault. Our model shows that tectonic processes can explain the exhumation of the western TW; erosional denudation seems to play only a minor part.