A more careful evaluation of some details, as the "fasces", the "volumina", and the "Tabellae", allows a new interpretation of the frieze on the arch of Susa. The North side represents the sacrifice offered to Jupiter by the Roman "legatus", to celebrate the annexation of the Alpine district in the Roma Empire and the entering as a prefect of Cottius I, present with his eldest son and heir Donnus II. In the West side the chiefs of 14 "civitates" swear faithfullness to Augustus in the presence of Cottius and Roman "legatus". In the South side Cottius offers a double sacrifice, to Jupiter and to Genius Augusti, in the occasion of the "constitutio" of the arch, in the presence of his two sons and of the prefect of the Alpes Maritimae, now responsible for some "civitates" previously ruled by Cottius. The East side very probably represents the census carried out by Cottius by order of Augustus, just after the grant of the "ius Latii" to the inhabitants of the district.