When nineteenth-century travellers reached Sepino, the imprint of the ancient city was clearly recognizable despite the abandonment, transformations and overlaps added within the town. The four monumental gates were easily outlined in the defensive perimeter but the collapses had opened other passes and created large gaps in the curtain walls. A long phase of wear and tear had irreparably affected the facings and the wall nuclei since, once the public function was lost, no one had taken charge of the protection of the city walls, exposing them to the processes of degradation. Since the Second World War, a large part of the wall system has been the subject of study and restoration work that has allowed the ancient layout to be brought back to light in almost its entirety. Preserving the opus reticulata masonry technique, a large amount of original material that was found in the collapse heaps and dispersed throughout the fields was recovered and relocated in the towers and rectilinear curtains, so that the monumental complex of the walls could once again return to its ancient splendour and show the expertise of Roman military engineering.