During the third season of excavation, we continued the investigation of the curvilinear structure to the west of the bath complex. With the aim of defining the precise plan as well as the character of this structure, the excavation sectors to the north and east of the emerging walls were expanded and a new sector about 30m to the west of the west edge of the excavation area was opened.

The continuation of investigations in the northern sector clarified the nature of a curving wall identified at the end of the previous season. It belongs to a still buried spiral staircase of which only the base of a window, a fragment of one of the treads, and the central column remain. The staircase must have led to at least one room underneath, the existence of which was already inferred since 2010 and which was apparently covered by a groin vault.

Excavation in the new sector, aimed at testing the results of 2011 geophysical surveys which suggested that the already emerging walls continued so as to form an elongated oval, brought to light new curving wall segments of identical type and layout to those already uncovered. The wall structures from both areas may therefore be attributed to a single building of elliptical shape, thus lending more weight to the hypothesis that we are dealing with the amphitheatre at Lanuvium where, according to the ancient sources, Commodus killed wild beasts.

The artifacts recovered consist mainly of large numbers of white and colored marble fragments, very numerous polychrome tesserae in glass paste, a number of brick stamps, especially anepigraphic ones, and ceramic fragments such as African slipware.

Future investigations will seek to define the exact plan and chronology of this building and to identify other structures in the adjacent areas.