Beneath the streets of the old centre of Naples lies another city, carved out of the tufa over two thousand years: Greek quarries, Roman cisterns, the wells families drew their water from until the nineteenth century and the shelters where people hid during the war. Napoli Sotterranea in piazza San Gaetano, on via dei Tribunali, takes you through it and then brings you back up inside a ground-floor home in the neighbourhood, where behind a door lies the vault of a Roman theatre.
Many people arrive convinced that «underground Naples» is a single place. In fact there are at least three undergrounds you can visit, run by different operators, with different tickets and entrances a long way apart: this article covers the one at piazza San Gaetano 69, not to be confused with the San Lorenzo Maggiore complex, a few metres away, or with the Galleria Borbonica, which is nineteenth century and opens on the other side of the city.
Bear in mind too that you can only go down with a guide, in a group, and the visit lasts about ninety minutes: the departure time you choose is what shapes your day.
Who was the munaciello really, the mischievous little monk who, in Neapolitan tradition, got into houses and moved things around?
Why there is a void the size of the city underneath Naples
How does a labyrinth on this scale form beneath an inhabited centre? It was not dug to be a labyrinth: it is the negative of the city sitting on top of it. Naples is built of yellow tufa, and the tufa was carried away from below. Every building in the old centre is made of the stone quarried on the very spot where the building then rose, and the emptied quarry stayed there, under the floor.
That is why the chambers you will walk through have the shape they have: walls that widen towards the bottom, like upturned bells. Quarrymen cut from above, lowering themselves through a narrow opening, and the deeper they went the wider the cut. That shape is not architecture, it is a working method printed into the rock.
The Greeks began in the fourth century BC, the Romans carried on, and when the quarries were no longer needed they were turned into cisterns, with waterproofed walls. The void had changed trade without changing shape.
The well-keepers, and the most convincing explanation of the munaciello
The cisterns were not connected to public fountains: they were connected to the houses. Every building had its own well, which dropped from the courtyard or even from the kitchen down to the water chamber, and the woman of the house lowered her bucket into her own private well. The photograph at the top of this article is exactly that: the shaft of a well seen from below, from the water’s side.
A system like that has to be kept clean, and the men who did it were a guild called the pozzari, the well-keepers. They climbed down from the wells of the houses using footholds cut into the vertical walls of the cisterns, and they worked in the dark in a place you cannot leave quickly. It was dangerous, badly paid work, and the pozzari were partly paid in kind by the families they served.
The munaciello, the mischievous little monk of Neapolitan tradition who gets into houses, moves objects, steals and sometimes leaves money, has a widely accepted explanation and it is entirely earthbound: he was the well-keeper. Men often of short stature, dressed in a short habit with a hood to keep the damp off, who climbed up the wells and emerged inside the house. Anyone who glimpsed one saw a small monk. It is the most widespread hypothesis rather than a documented certainty, but it is by far the simplest.
How it ended: the cholera of 1884, and the sewer that ran above the aqueduct
Why was a network that had worked for two thousand years shut down within a few months? Not because the water was dirty in general, but because of a problem of levels, chilling in its simplicity.
Naples was served by two aqueducts. The Bolla, which came from Volla, ran largely in the open and was exposed to contamination. The Carmignano ran underground and was maintained by the well-keepers, but it was riddled with seepage. The trouble was that the sewer network ran above the aqueduct, and tufa is a permeable stone: liquids filtered downwards, from the sewer into the drinking water.
In 1884 the cholera epidemic made the mechanism plain and the Kingdom of Italy decreed the definitive closure of the Bolla. Out of that epidemic came the Risanamento, the great rebuilding that demolished entire old quarters of the city. With the new aqueduct the underground lost its purpose, and the wells of the houses were bricked up one by one. The void stayed there, forgotten, for sixty years.
The air-raid shelters, or the second life of the void
In the Second World War those same chambers became useful again in a way nobody had planned: they were the air-raid shelter already in place, under the house, where Neapolitans went down during the bombing and where many families lived for weeks.
What you will see is not a reconstruction: it is the partition walls put up to give each family its corner, the camp beds, the objects left behind, the toys, and above all the writing and drawings on the tufa walls. It is the part of the visit where the group falls silent by itself, because you pass from antiquity to the twentieth century without changing room.
The Roman theatre inside a ground-floor flat, and the night Nero sang
The last part of the visit is what makes this route unlike any other Italian underground, and it starts by going back up to the street. You walk into a basso in vico Cinquesanti, a ground-floor dwelling in the old centre. You pass a wardrobe with mirrored doors, you push a door aside, and behind it is the vault of the Roman theatre of Neapolis.
The theatre was not excavated and cleared: it was swallowed. The buildings of the old centre grew over it and into it across twenty centuries, and today the curve of the cavea can be read in the bend of via Anticaglia, where two arches cross the street from one building to another. The people who live here share their home with a Roman monument that holds up their wall.
An ancient story belongs here, with the caution it deserves. Tacitus, in the Annals, and Suetonius, in the Lives of the Caesars, report that Nero made his debut as a singer in Naples, before a Greek audience, because the city struck him as the right place to try himself out before facing Rome. During those performances there was an earth tremor, and the emperor read it as a sign of divine approval rather than a warning, carrying on singing and keeping the audience in their seats. Suetonius also describes whole days on stage, with meals served to him there.
Warning: the ancient sources say «at Naples», not «in this building». Identifying it with the theatre whose vault you are looking at is the current scholarly assumption, and a reasonable one because this was the city’s theatre, but no Roman author writes it down for us. Be wary of anyone telling it to you as established fact: the story is good enough without being forced.
Practical information
Details checked on 9 September 2026. Prices and opening times change: check again before you travel.
Tickets. The full ticket costs 15 euros and covers the complete guided visit, which is the only way in. There is no admission-only ticket.
Opening times. Tours in Italian leave every hour from 10:00 to 18:00. Tours in English leave at 12:00 and 14:00. On Thursdays there is an evening tour at 21:00, but only by booking and with a minimum of ten people. There is no weekly closing day, which makes underground Naples one of the three visits on this itinerary that save a Wednesday, along with Santa Chiara and the Pio Monte della Misericordia.
Getting there. The entrance is at piazza San Gaetano 69, on via dei Tribunali, in the heart of the old centre. From metro line 1 get off at Dante or Museo and walk about ten minutes. Do not come by car: the area is pedestrian and restricted.
How long it takes. About ninety minutes, guide included. Plan to turn up at least a quarter of an hour before your slot leaves.
What to wear. Down below the temperature stays around fifteen degrees all year, so in summer bring something to put on. You need closed shoes with a sole that grips, because in places the floor is uneven. Warning: part of the route runs through very narrow passages, about the width of a person and walked with a candle in hand. That stretch can be skipped without leaving the group, but if you are claustrophobic it is better to know before you go down rather than halfway along.
The rest of Naples
The old centre you walk on the surface is the same Greek grid you are crossing twenty metres below: the three decumani are still the three main streets. The complete two-day route is in what to see in Naples in 2 days.
A hundred metres from here, on the same decumanus, are the cathedral with the treasure of San Gennaro and the Pio Monte della Misericordia with its Caravaggio, and a little further down the Sansevero Chapel and the majolica cloister of Santa Chiara. If the underground has got hold of you, the other excavated Naples is the catacombs, which I cover in the Sacred Mile of the Rione Sanità.
What the Romans left above ground is almost all in the Archaeological Museum, while up on the hill the monastery with the view is the Certosa di San Martino. The Bourbon Tunnel, the third of the Neapolitan undergrounds, opens instead under the hill of Pizzofalcone, on the other side of the centre.
Photo credits: well seen from the cistern and Roman theatre by Dominik Matus (CC BY-SA 4.0); tufa quarry by Armando Mancini (CC BY-SA 2.0). All from Wikimedia Commons.
