Augusta Praetoria Salassorum was the Roman colony founded by Emperor Augustus to secure control over the routes crossing the Alps. It corresponds to present-day Aosta. From this crucial road junction, the consular road from Mediolanum (Milan) split into two main routes towards Gaul: one crossed the Little Saint Bernard Pass and continued to Lugdunum (Lyon), while the other crossed the Great Saint Bernard Pass and led to Octodurus (Martigny).
It is worth noting that the Roman settlement’s name preserves several layers of historical meaning. The colony was called Augusta in honour of Emperor Augustus, who founded it in 25 BC; Praetoria because around three thousand Roman army veterans were settled there and entrusted with guarding the area; and finally Salassorum, because these lands, inhabited since prehistoric times in the Saint-Martin-de-Corléans area, had long been associated with the Celtic population of the Salassi. Rome attempted several times to subjugate this Alpine people. As early as 143 BC, the consul Appius Claudius Pulcher achieved a significant victory against them, but only in 25 BC did the legions led by Aulus Terentius Varro Murena succeeded in permanently defeating the Salassi, paving the way for the foundation of the new colony. The strategic and military importance of Augusta Praetoria in controlling the region is therefore clear.
The Arch of Augustus in Roman Aosta
Along the Via delle Gallie, travellers reached Augusta Praetoria after passing through the Arch of Augustus. The monument was erected in honour of the colony’s founder and served to display Rome’s power to the conquered people. The arch consists of a single barrel vault passage and rests on massive piers made of conglomerate stone blocks. Ten half-columns featuring Attic bases and Corinthian capitals decorate the structure. Of the original decorative elements, only the Doric entablature with its triglyphs and metopes survives, while the attic was lost during the eighteenth century.
The urban structure of Roman Aosta
Augusta Praetoria followed the principles of Roman urban planning, and the settlement had a characteristic rectangular layout. Its dimensions depended on the slope of the valley floor surrounded by mountains. The Buthier River to the east and the Dora Baltea River to the south also defined its natural boundaries. People could enter the city through gates located at the ends of the decumanus maximus, which continued the route of the Via delle Gallie: the Porta Praetoria and the Porta Decumana.
The main cardo crossed the decumanus maximus at a right angle near the city’s forum, the centre of the colony’s political, administrative and commercial life. The Porta Principalis Sinistra and the Porta Principalis Dextera marked the ends of the city along its north-south axis. Defensive walls enclosed the entire urban structure. Their layout has survived almost intact to the present day. The walls were built in opus caementicium, using river stones bound with mortar.
Porta Praetoria
The Porta Praetoria, the main entrance to the Roman city, was built with blocks of stone and slate. Only a few sections of the original grey-green and white marble facing have survived. The gate consists of two opposing rows of arches, each featuring three openings: the central passage, which was wider, was intended for carts, while the side passages were used by pedestrians. Portcullises fitted into the outer openings protected the city. The two defensive towers flanking the structure also date back to the Roman period. However, later alterations changed their appearance over the centuries.
The forum and cryptoporticus of Aosta
The Forum complex of Augusta Praetoria stood at the intersection of the decumanus maximus and the main cardo. The area was characterised by a natural slope running from north to south, making it necessary to create an artificial terrace to overcome the difference in elevation. Hence, at the top of this platform stood the sacred area, where two twin temples were located, probably dedicated to Rome and Augustus. Below it extended the public square, which served as the centre of civic activities.
An almost entirely preserved cryptoporticus enclosed the sacred area. It consists of a semi-underground gallery approximately two hundred metres long, arranged along three sides and characterised by a double corridor with low arches. The structure features travertine pillars and barrel vaults. Archaeologists believe that the cryptoporticus served as a storage area for goods used by the workshops and tabernae that opened onto the forum. Above it stood an elegant marble colonnade framing the temples.
The ludi area in Roman Aosta
In the north-eastern part of Augusta Praetoria‘s urban layout stood the city complex devoted to public spectacles, known as the ludi. It included a monumental theatre, capable of accommodating up to four thousand spectators, as well as an amphitheatre.
The Roman theatre of Aosta does not date back to the foundation of the city under Augustus but to a later phase, probably around the middle of the first century AD. The southern façade has survived in an exceptionally well-preserved condition. Its remains provide valuable evidence of what the theatre must have looked like two thousand years ago.
The surviving façade shows that a building more than twenty metres high enclosed the entire cavea, probably provided with a roof to protect spectators from the heavy winter snowfall. The southern elevation, marked by imposing vertical buttresses and built with large blocks of stone and travertine, has an external surface finished with rough rustication. A series of round arches characterises the lower level, which supports three tiers of windows. The scale of the building can be appreciated by considering that the summa cavea reached the level of the upper openings. Only the foundations of the stage area remain. However, historical evidence indicates that the façade was once decorated with Corinthian columns, marble elements and statues.
Aligned with the theatre stood the city’s amphitheatre. Today, only a few arches of its outer perimeter survive, incorporated into the convent of the Sisters of Saint Joseph. It has not yet been established whether the amphitheatre, which could once accommodate around fifteen thousand spectators on two levels of seating, formed part of Augusta Praetoria‘s original urban plan or whether it was built at a later date.
Samuele Corrente Naso
Bibliography
L. Appolonia, M.C. Fazari, Il Teatro romano di Aosta, Aosta, 2005.
C. Promis, Le Antichità di Aosta, Torino 1962, ristampa anastatica, Sala Bolognese, 1979.
A. Zanotto, Valle d’Aosta antica e archeologica, Aosta, 1986.
