The Roman amphitheatre of Aosta (Augusta Prætoria Salassorum) is located inside the Roman walls and its ruins are incorporated in the monastery of the nuns of St. Catherine. It is speculates that it dates back to the I century A.D. The elliptical arena was 86 meters north-south and 73 in east-west direction. The cavea could accommodate about 15,000 spectators. Afterwards the amphitheatre fell into ruin and was employed as a quarry of material for the construction of other buildings.