Tridentum: the Roman city beneath Trento, walkable underground at the SASS
Under the paving of Piazza Cesare Battisti in the centre of Trento, beneath the Teatro Sociale, lies a secret: 1,700 square metres of the Roman city of Tridentum, a whole quarter of streets, walls, houses and mosaics that you can walk through underground. The emperor Claudius called Tridentum a splendidum municipium, a splendid town, and at the SASS, the Spazio Archeologico Sotterraneo del Sas, you step down out of the modern square into the city that was here two thousand years ago. It is one of the most atmospheric archaeological visits in the Alps.
Most Roman sites ask you to imagine the city that once stood where you see ruins in the open air. The SASS does the opposite: it takes you down beneath a living city square into the preserved streets of the ancient one, so that you walk the Roman town with the modern town directly overhead. That vertical relationship, the city beneath the city, is what makes Tridentum so memorable, and it makes the visit a perfect choice for a wet day, a winter afternoon, or a family that needs an indoor adventure, in a region better known for mountains and Christmas markets than for Roman archaeology.
Tridentum, the splendid town on the Adige
The Romans founded Tridentum around the middle of the 1st century BC for a clear strategic reason: to hold the valley of the Adige, one of the great corridors between central Europe and the Mediterranean. In 46 AD the emperor Claudius referred to it as a splendidum municipium, a splendid town, and the phrase has stuck to the city ever since. The original Roman town covered about thirteen hectares in a regular grid of broad streets crossing at right angles, ringed by a wall with towers and a moat and protected on the north by the original course of the Adige. Over its long life, from the 1st century BC to the 6th century AD, Tridentum was repeatedly altered and finally absorbed into the medieval and modern city, which simply rose on top of it. The acronym SASS recalls the old Sas quarter of Trento, partly demolished in the 1930s to create the present square, the works that eventually led down to the Roman city below.
Walking the city under the city
The Roman quarter came to light in the 1990s, during the restoration and extension of the Teatro Sociale, and it has been preserved and opened as an underground route. Down in the cool, dim space you walk an extensive stretch of the eastern city wall, with the remains of a tower that was later turned into a city gate, and a long segment of a minor decumanus paved with large slabs of local red stone. Beneath the street run the channels of an elaborate Roman sewer system, a reminder of how seriously Roman cities took drainage. Around the street you can see parts of houses with their domestic rooms, floors decorated with mosaics, rooms fitted with underfloor heating, a courtyard, a perfectly preserved well, and, memorably, the workshop of a glassmaker. A trilingual audioguide and an optional virtual-reality experience, Tridentum VR, help bring the quarter back to life. It is compact, but the sense of moving through real Roman streets beneath the modern piazza is extraordinary.
The rest of buried Tridentum
The SASS is the showpiece, but it is part of a wider buried city. Elsewhere in central Trento you can visit the Roman Villa of Orpheus in Via Rosmini, the archaeological area under Palazzo Lodron, and the early Christian basilica beneath the Duomo, while the Porta Veronensis under the Civic Tower in Piazza Duomo has at times been closed. Together these fragments let you assemble Roman Trento from beneath the streets of the modern one, a genuinely unusual way to read a city.
| Inside the SASS | What it shows |
|---|---|
| City wall and tower | The eastern defences, the tower later made into a gate |
| Paved street and sewers | A minor decumanus in red stone over an elaborate drainage system |
| Houses | Mosaic floors, underfloor heating, a courtyard and a well |
| Glassmaker's workshop | A trace of everyday industry in the Roman town |
A short history in dates
- mid 1st c. BC Rome founds Tridentum to control the Adige valley.
- 46 AD The emperor Claudius calls Tridentum a splendidum municipium.
- 1st c. BC to 6th c. AD The Roman city lives, is altered and is gradually absorbed into the later town.
- 1930s The old Sas quarter is partly demolished to create Piazza Cesare Battisti.
- 1990s Restoration of the Teatro Sociale uncovers the Roman quarter now shown at the SASS.
- today The SASS and other buried sites let visitors walk Roman Trento beneath the modern city.
What nobody tells you
This is the rare archaeological site that is better in bad weather. Because it is entirely underground and indoors, the SASS is the perfect rainy-day or winter stop in Trentino, cool in summer and dry in any season, and it works beautifully for families and children, who love the idea of a hidden city under the square. Download the free trilingual audioguide before you go down, because it carries most of the interpretation, and ask about the Tridentum VR experience if you want the streets reconstructed around you. It is compact, so an hour or so does it, which makes it easy to combine with the rest of Trento, the castle, the cathedral and the mountains beyond. And if you hold a Trentino Guest Card, entry is included.
Who should skip the SASS
Honest version. If you want a sprawling open-air Roman city to wander for hours, the SASS is a single compact underground quarter of about 1,700 square metres, not a vast site, so set your scale accordingly. If you are claustrophobic, note that it is an enclosed underground space. And if you will not use the audioguide, some of the meaning will pass you by. But if the idea of descending beneath a city square to walk the real streets of a Roman town thrills you, if you want a perfect indoor stop for a wet or cold day in the Alps, and if mosaics, underfloor heating and a Roman glassmaker's workshop under modern Trento sound like an hour well spent, the SASS is one of the most original archaeological experiences in northern Italy.
Why the Adige valley mattered so much
The reason Rome bothered to plant a splendid town this far up into the Alps comes down to one of the most important facts of European geography: the Adige valley is a corridor. It is one of the few routes by which you can pass through the Alps without crossing a high, snowbound col for much of the way, a natural highway running north toward the Brenner Pass and on into the lands of central Europe, and south toward the Po plain and the Mediterranean. Whoever held the Adige valley held the traffic, military and commercial, between the Roman world and the peoples beyond the mountains, which is exactly why Tridentum was founded where it was, walled and towered and set to watch the river. That strategic logic outlived Rome by two thousand years. The same valley carried medieval trade and pilgrims, became a fought-over frontier in the First World War, and today funnels the motorway and the main rail line between Italy and the Brenner. So the buried Roman streets at the SASS are not a backwater curiosity, they are the deepest layer of a crossing point that has mattered continuously since antiquity, the reason there has always been a city here and always will be.
Frequently asked questions
- What is the SASS in Trento?
- The SASS, or Spazio Archeologico Sotterraneo del Sas, is an underground archaeological space beneath Piazza Cesare Battisti and the Teatro Sociale in Trento, preserving a 1,700 square metre quarter of the Roman city of Tridentum, with streets, walls, houses, mosaics and a glassmaker's workshop that you can walk through.
- What was Tridentum?
- Tridentum was the Roman city founded around the mid 1st century BC on the site of modern Trento to control the strategic Adige valley. The emperor Claudius called it a splendidum municipium, a splendid town, in 46 AD, and the medieval and modern city rose directly on top of it.
- What can you see at the SASS?
- A long stretch of the eastern city wall with a tower later turned into a gate, a paved minor decumanus in local red stone with an elaborate sewer system beneath it, houses with mosaic floors and underfloor heating, a courtyard, a perfectly preserved well, and the workshop of a glassmaker.
- How much does it cost to visit the SASS?
- Entry is paid, and it is free with the Trentino Guest Card. A trilingual audioguide in Italian, English and German is free to download. Confirm current prices on the official Trentino Cultura site.
- What are the opening hours?
- The SASS opens roughly Tuesday to Sunday with a morning and an afternoon session, closed Monday except holiday Mondays, and closed on 25 December and 1 January. Always check the official Trentino Cultura schedule before visiting.
- Is the SASS a good rainy-day or winter activity?
- Yes, ideally. Because it is entirely underground and indoors, it is cool in summer and dry in any season, making it a perfect wet-day or winter stop in Trentino, and it works well for families and children intrigued by a hidden city beneath the square.
- Are there other Roman sites in Trento?
- Yes. Besides the SASS, you can visit the Roman Villa of Orpheus in Via Rosmini, the archaeological area under Palazzo Lodron, and the early Christian basilica beneath the Duomo, while the Porta Veronensis under the Civic Tower has at times been closed. Together they let you assemble Roman Trento beneath the modern city.
- How do you get to the SASS?
- It is in central Trento and reached on foot, with the entrance in Piazza Cesare Battisti beneath the Teatro Sociale. Trento is on the Verona to Brennero rail line, and there is accessible parking about 100 metres away in Via Manci.
- Why did the Romans found Tridentum in the Adige valley?
- Because the Adige valley is a natural corridor through the Alps toward the Brenner Pass, linking the Roman world to central Europe. Holding the valley meant controlling the traffic between the two, so Rome founded the walled town of Tridentum to watch the river, on a crossing point that has mattered continuously ever since.