The 1st Century AD Porta Praetoria was once the eastern gate to the city of Aosta. It is well preserved but lacks its original marble covering. Made up of a series of arches, it encloses a small square. The walls have three arches, the central one being larger than the other two to enable carts to pass through. It was constructed using huge square blocks of stone. The external wall is 4.50m. wide, while the inner one is 3.45m. Because of the elevation of the ground, the gate is now 3 metres underground.