Between January and March 2000 an excavation was undertaken in the attic of the arch of Trajan, Benevento, as part of the general restoration of the entire monument. The aim was an analysis of the structures present on the summit of the arch and a reconstruction of their development. The need to put in a new covering made it necessary to survey and map the structural elements exposed by the partial dismantling of the most recent (1970s onwards) covering. Among the material used for these interventions, it was possible to identify evidence of earlier construction phases, probably antique. Therefore, before any decisions could be made about future interventions it was necessary to make a precise evaluation of the state of the structures. The recovery/restoration of the Trajan’s arch presents two types of problem. The first is of a practical nature and immediately apparent, linked to political-economic-administrative considerations relating to the funding and carrying out of the interventions. The second problem is theoretical and wider ranging, linked to the choice of the methodology and materials to be used for the restoration.