Built in 25 B.C. on the occasion of Roman victory over Salassi by Aulus Varro Murena. In line with decumanus maximus, it is not far from Bourg Saint-Ours (district of Sant'Orso) and from the eastern entrance of City Walls (Porta Praetoria). It is built of conglomerate blocks and has a single barrel-vault. In the monument will recognize different styles: ten semi columns that adorn the facades and the sides culminate in Corinthian capitals, while the entablature, adorned with metopes and triglyphs, is Doric. Today's appearance is the result of the last restoration and consolidation took place in 1912 by Ernesto Schiaparelli. Wooden crucifix under the vault is a copy of what was placed there in 1449 as a votive offering against flooding of Buthier River, which flows just east. Original cross is now housed at Museum of Treasure of Cathedral.