The town plan followed the scheme of the Romans military camp, the castrum, with two main axes, the longer decumanus maximus who was also usually a main Roman road. Actually the construction plan took advantage of all the engineering knowledge of the Romans, with the long side of 724 meters and the short of 572, the main axis parallel to the valley created by a meander of the Buthier stream, just before it flows into the Dora river.
The town was all surrounded with walls and fortified towers, with the main entrance called Porta Praetoria, still extant, built with huge blocks and sided by two square towers. The decumanus maximus was part of the road coming from Gallia, crossed the town and passing under the western door proceeded towards Rome. Inside the town are the theatre and amphitheater, the forum, of which the sacred area consisting of a platea and basilica are still visible, and some locals of the thermae, located in the vicinity of the present Townhall palace.
More info on the town of Aosta