# Aosta: the Roman city is still the street plan

> Aosta was laid out in 25 BC inside walls enclosing 414,128 square meters. Four Roman monuments still stand, plus a sanctuary 6 meters under the road.

URL: https://myitalia.it/towns/aosta
Last updated: 2026-09-02

Aosta was founded in 25 BC as Augusta Praetoria Salassorum, its walls enclosed 414,128 square meters with four gates, and it holds more visible Roman remains than any Italian town except Rome.

## The grid of 25 BC is the grid you walk

The colony went up in 25 BC on a rectangle of 414,128 square meters, with four gates in the circuit wall. One of them, the Porta Praetoria, is still standing, and so are the theater, the forum cryptoporticus, the Roman bridge and the Arch of Augustus.

That concentration is the reason to stop here rather than only pass through on the way to the ski valleys. You can cross the whole Roman town on foot in under half an hour.

## The arch that mixes two orders

The Arch of Augustus was raised in 25 BC for the victory over the Salassi won by Aulus Terentius Varro Murena, with a single opening 11.40 meters high to the keystone.

Look up at the decoration and you see the compromise: ten half columns with Corinthian capitals carrying a Doric entablature with metopes and triglyphs. The two orders do not normally meet, and here they do, in a garrison town on a new frontier.

## Twenty-two meters of theater facade

The southern facade of the Roman theater still stands 22 meters (72 feet) high, and it is the piece of Roman Aosta you see from the furthest away. It was built a few decades after the founding of 25 BC.

Behind it the seating covered an area of 81 by 64 meters and held between 3,500 and 4,000 spectators. For a colony that size, that is a large building, which tells you what Rome expected the place to become.

## The gate, and how far the ground has risen

The Porta Praetoria was the eastern entrance of the Roman town, built in 25 BC as a double screen of arches with a courtyard between them and two rectangular towers. The central opening is 7 meters across for carts, flanked by two passages of 2.65 meters for people on foot.

Excavations in 2012 and 2013 found the Roman paving 2.5 meters under today's street. Stand in the gate and you are standing well above the level the carts used, which is why the arches look shorter than they were built.

## A sanctuary six meters under the road

The megalithic area of Saint-Martin-de-Corléans lies 6 meters below street level, under a museum building of 9,820 square meters spanned without columns for 46.5 meters. The excavated sanctuary covers an area given as 10,000 square meters.

People used the site from the last centuries of the fifth millennium BC to the early Bronze Age, leaving anthropomorphic stelae, ritual pits, alignments of wooden posts, dolmen tombs and cist burials. The museum opened on June 24, 2016, reopened in November 2023, and has been called the MegaMuseo since February 2025. There is more at [a prehistoric sanctuary under a city](/stories/a-prehistoric-sanctuary-under-a-city) and at [things to do in Aosta](/towns/aosta/things-to-do).

## FAQ

### How much Roman Aosta is actually left?

Enough that the town keeps the largest set of visible Roman remains in Italy after Rome. The walls of 25 BC enclosed 414,128 square meters with four gates, and the theater, the forum cryptoporticus, the Roman bridge and the Arch of Augustus are all still standing.

### How big was the Roman theater in Aosta?

The seating area covered 81 by 64 meters and held between 3,500 and 4,000 people. What survives above ground is the southern facade, 22 meters high, built a few decades after the city was founded in 25 BC.

### Can you walk through the Porta Praetoria?

Yes, it is a public passage. The central opening is 7 meters wide, built for carts, with two side passages of 2.65 meters for pedestrians. Excavations in 2012 and 2013 found the Roman paving 2.5 meters below the modern street surface.

### What is in the megalithic museum in Aosta?

A prehistoric sanctuary excavated 6 meters below street level: anthropomorphic stelae, ritual pits, lines of wooden posts, dolmen and cist burials. The museum opened on June 24, 2016, reopened in November 2023 and took the name MegaMuseo in February 2025.

### Why was the Arch of Augustus built?

To mark the Roman victory over the Salassi led by Aulus Terentius Varro Murena, in 25 BC, the year the colony was founded. The opening is 11.40 meters high to the keystone, and ten half columns with Corinthian capitals carry a Doric entablature.

## Sources

| Fact | Source | Confidence | Valid until |
|---|---|---|---|
| Aosta nasce nel 25 a.C. come Augusta Praetoria Salassorum: la cinta muraria romana racchiudeva 414.128 metri quadrati con quattro porte, e la citta' conserva il maggior numero di resti romani ancora visibili in Italia dopo Roma | [Wikipedia](https://it.wikipedia.org/wiki/Aosta) | medium | 2099-12-31 |
| L'Arco di Augusto di Aosta fu eretto nel 25 a.C. per la vittoria romana sui Salassi guidata da Aulo Terenzio Varrone Murena: ha un fornice alto 11,40 metri sotto la chiave di volta e mescola dieci semicolonne con capitelli corinzi a una trabeazione dorica con metope e triglifi | [Wikipedia](https://it.wikipedia.org/wiki/Arco_di_Augusto_(Aosta)) | medium | 2099-12-31 |
| Del teatro romano di Aosta, costruito qualche decennio dopo la fondazione della citta' del 25 a.C., resta in piedi la facciata meridionale alta 22 metri: la cavea occupava un'area di 81 per 64 metri e ospitava fra 3.500 e 4.000 spettatori | [Wikipedia](https://it.wikipedia.org/wiki/Teatro_romano_di_Aosta) | medium | 2099-12-31 |
| La Porta Praetoria, ingresso orientale di Augusta Praetoria costruito nel 25 a.C., e' una doppia cortina di archi con un cortile interno fra le due: fornice centrale largo circa 7 metri per i carri e due passaggi laterali da 2,65 metri per i pedoni; gli scavi del 2012-2013 hanno ritrovato il selciato romano circa 2,5 metri sotto il piano stradale odierno | [Wikipedia](https://it.wikipedia.org/wiki/Porta_Praetoria_(Aosta)) | medium | 2099-12-31 |
| L'area megalitica di Saint-Martin-de-Corleans, dentro Aosta, e' un santuario preistorico di circa 10.000 metri quadrati scavato sei metri sotto il livello stradale: e' stato frequentato dagli ultimi secoli del V millennio a.C. all'eta' del Bronzo, il museo e' stato inaugurato il 24 giugno 2016 ed e' stato riaperto nel novembre 2023, assumendo il nome MegaMuseo nel febbraio 2025 | [Wikipedia](https://it.wikipedia.org/wiki/Area_megalitica_di_Saint-Martin-de-Corl%C3%A9ans) | medium | 2029-12-31 |

## Image

https://media.myitalia.it/media/city.aosta.1600.jpg
Author: Krzysztof Golik. License: CC BY-SA 4.0 (https://creativecommons.org/licenses/by-sa/4.0).
Source: https://commons.wikimedia.org/wiki/File:Town_hall_of_Aosta_(1).jpg

## Other languages

- it: https://myitalia.it/it/paesi/aosta.md
- es: https://myitalia.it/es/pueblos/aosta.md
- fr: https://myitalia.it/fr/villages/aosta.md
- de: https://myitalia.it/de/orte/aosta.md