In 1994, preliminary investigations were undertaken in the area of Ca’di Ratt. Work has resumed there on the investigation of the Roman amphitheatre in the areas still free of buildings, south of the Roggia Molinara, in the locality of Prati Sparviero.

The foundations of a section of the amphitheatre’s cavea were exposed, situated south of the city between Viale delle Rimembranze and Corso De Rege, and partially obliterated by the walls of later buildings. The structure, marked on a map made in 1610 came to light in 1928 during work on the Roggia Molinara. On an almost perfectly west-east alignment and measuring c. 107 × 90 m, it has a slightly accentuated ellipse and rounded arena and is of the type with a solid/masonry-built structure. The interior structure is characterised by three maeniani , the innermost one almost completely removed by a robber trench, and the outermost built of cobblestone conglomerate, forming platforms about 8 and 11 m wide. The central maeniano had a system of radial substructures that supported the segmented earthwork. At the level of the maeniano, in correspondence with the western entrance, a large room opened on the main axis. Its walls were in ¬opus vittatum mixtum of cobblestones alternating with double brick courses and it was perhaps a sacellum or service room. The fill from the partial excavation of this room contained fragments of large Luna marble slabs and pieces of a small slab with refined decoration of marine motifs, once part of the decorative scheme on the arena podium. The excavation was able to check the original floor levels of the entrance given that the actual line of the Roggia Molinara di Parolo follows that of the main axis.

No finds were recovered that could be used for defining the amphitheater’s chronology. However, based on comparisons with similar structures in the Piemonte region, a date relating to the urbanisation of the municipium of Vercellae between the second half of the 1st century A.D. and the beginning of the 2nd century A.D. may be suggested. Some occupation of the area following the destruction of the amphitheatre was attested by the presence of five burials in partially disturbed earth graves, generically datable to the medieval period due to the absence of grave goods, and by a brick and cobblestone structure on a north-west/south-east alignment associated with several post-holes. This structure was built on top of the rubble fill of the service room and partially abutting it. Again, due to the lack of datable finds it can only be dated to a period between the late medieval period and the time when the Sabaudian citadel was enlarged on the initiative of Carlo Emanuele I from 1610 onwards.