The Szebény Viaduct is the biggest and technically most complex bridge on motorway M6. The bridge spans a wide valley and a watercourse at the 176.9 km section. We requested to have the 866-meter long bridge designed according to the twin-cell orthotropic carriageway concept, assuming that each of the innermost 7 unsupported lengths would span 100 meters. In contrast to the composite structure or reinforced concrete structure concept envisaged in the tender design and the original proposal, respectively, we opted for the steel structure version, because the 92-meter long southernmost span of the bridge flies over the ruins of a Roman villa, a valuable archeological finding. Therefore, the construction of any provisional supporting structure was prohibited.