CELEBRATION 2000 was a large international experiment that focused on the lithospheric structure in Central Europe. It consisted of several wide-angle reflection and refraction seismic profiles. Profiles CEL01 and CEL04 are located in the transition from the Precambrian and Palaeozoic platforms to the Carpathian orogen. The data were modelled using 2-D tomographic and forward modelling techniques. The profile CEL01 (about 900 km long) extends from the southwestern margin of the East European Craton to the Pannonian basin system. The depth of Moho boundary varies along the profile from 27–33 km under the Pannonian basin system area, 30–39 under the Carpathians and within the TESZ to 40–45 km under the East European Craton. The CEL04 profile (630 km long) starts in the Polish trough (PT) and reaches the Pannonian basin system. Along the CEL04 profile, the Moho interface shallows from 40 km beneath the PT to about 35 km in the Maopolska unit. The crustal thickness is 43 km beneath the Carpathians and 25 km beneath the Pannonian basin system. The results obtained are consistent with a commonly accepted view of the Carpathians, thought to be formed largely due to the interplay between Palaeogene to Middle Miocene subduction of oceanic or suboceanic crust and subsequent collision. A feature that we interpret as the subduction-related orogenic root is at least partially preserved in both profiles and is manifested by a crustal thicknesses of 39 km (CEL01) and 43 km (CEL04). The boundary between the Małopolska unit and the Bruno–Silesian unit is discernible north of the Carpathian frontal thrust along the CEL01 profile, but is not observed farther to the southeast (CEL04) beneath the Carpathians. In the Pannonian basin system, no substantial differences in the crustal structure across the Mid-Hungarian Line were observed. Upper mantle reflections observed along both profiles originate from a north-Dipping mantle discontinuity, probably representing a shear zone related to collision and possibly ongoing convergence between the European plate and ALCAPA (Alps-Carpathians–Pannonian).