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Hidden gem1st c. BC – 3rd c. ADTicketed

Piscina Mirabilis

Piscina Mirabile

cistern · Campania, Italy

What it is
The Piscina Mirabilis is a vast underground Roman reservoir on the hill above the old naval harbour of Misenum, in Bacoli on the Gulf of Naples, and the reason to come is the inside: a hall of vaulted aisles carried on 48 pillars, which locals call the "Cathedral of Bacoli" (en.wikipedia).
What you’ll see
The cistern itself, nearly intact (en.wikipedia). Published figures put it at 70–72 m long, 25–26 m wide and 15 m high, and it held about 12,600 m³ of water (Pleiades; en, it and de.wikipedia; the ticket office).
Worth the trip?
Yes, if you can fit its timetable. This is one of the largest cisterns the Romans built (en.wikipedia), and it is a Roman interior you can walk through, vaults and all, rather than a plan at ground level.
Getting there & cost
The entrance is at Via Piscina Mirabile 27 in Bacoli, a few hundred metres from the town centre.Ticketed · €5 · checked 22 October 2026Hours, tickets and parking
A lane running beside a high, overgrown wall of tufa and banded brick with diamond-pattern facing, set with buttresses, and a modern house at the far end.
The outside wall of the cistern and its buttresses. · Photo: Tyler Bell · CC BY 2.0 · Wikimedia Commons
A long aisle inside the cistern, a row of tall arches on massive piers receding into the distance, with damp stained walls and green moss covering the floor.
Down one of the aisles of the cistern, between its piers. · Photo: Vernetto at it.wikipedia · Public domain · Wikimedia Commons
An 18th-century engraving of the cistern opened up in section, five tall arched aisles side by side under a ground line with trees, two small figures and a ladder on the floor, and a title in Italian and Latin below.
The interior as engraved for Paolo Antonio Paoli's book on the antiquities of Pozzuoli, Cumae and Baiae, 1768. · Photo: Natali, Giovan(ni) Battista (delin.) & Volpato, Giovanni (sculp.) · Public domain · Wikimedia Commons

What is there today

The cistern itself, nearly intact (en.wikipedia). Published figures put it at 70–72 m long, 25–26 m wide and 15 m high, and it held about 12,600 m³ of water (Pleiades; en, it and de.wikipedia; the ticket office). Four rows of twelve cross-shaped pillars divide it into long aisles, under barrel vaults; light and air came in through windows along the top of the side walls and through openings in the roof (it.wikipedia). In the central aisle is a settling basin 1.1 m deep, used to clean and drain the cistern (en and it.wikipedia). The walls and pillars are faced in opus reticulatum and were lined with waterproof plaster. Of the two staircases, only the north-western one still leads down into the main aisle (en.wikipedia).

From outside it is far less: a long wall of tufa and brick with buttresses, beside a lane.

Is it worth the trip?

Yes, if you can fit its timetable. This is one of the largest cisterns the Romans built (en.wikipedia), and it is a Roman interior you can walk through, vaults and all, rather than a plan at ground level. The visit is short, about an hour, so it pairs well with the Baia baths park 2.7 km away and with the Cento Camerelle, another cistern complex about 500 m away that has a combined ticket.

The catch is access. It opens only three days a week, entry is accompanied, every 30 minutes, booking is compulsory and you wear a helmet. Visitors who cannot manage stairs should ask the ticket office first.

Getting there and what it costs

The entrance is at Via Piscina Mirabile 27 in Bacoli, a few hundred metres from the town centre. From Naples, the ticket office gives bus 101 from Via Cristoforo Colombo or Molo Beverello to the Via Risorgimento stop in Bacoli, then about 6 minutes on foot; or Line 2 to Campi Flegrei, bus 101 to Via Lungolago and a 10-minute walk; or the Cumana railway to Torregaveta and the bus to Bacoli Centro. Drivers can park near the entrance, at the car park of the Azienda Agricola Piscina Mirabile (CoopCulture). OpenStreetMap maps an EAV bus stop about 260 m away.

A ticket is €5, €2 from 6 to 17, free under 6, and €8 for a one-day ticket that adds the Cento Camerelle. From October 2026 to March 2027 it opens Friday, Saturday and Sunday, 10.00–15.30; from April to September 2027, Friday 10.00–15.30 and Saturday and Sunday 10.00–16.30. The ticket buys accompanied entry, not a guided tour (CoopCulture, the ticket office the Parco Archeologico dei Campi Flegrei links to, read 22 October 2026). The Campi Flegrei are volcanically active, and the park refunds tickets when a site closes because of ground movement, so check on the day.

Visiting details

Opening hours
Entry is accompanied, every 30 minutes, and must be booked. From 1 October 2026 to 31 March 2027: Friday, Saturday and Sunday, 10.00–15.30. From 1 April to 30 September 2027: Friday 10.00–15.30, Saturday and Sunday 10.00–16.30. Closed on the other days. A visit takes about an hour.
Tickets
€5; €2 from 6 to 17; free under 6, for disabled visitors with a companion and for tour guides. €8 for a one-day combined ticket with the nearby Cento Camerelle. The ticket covers accompanied entry, not a guided tour.
Parking
The ticket office points to a car park near the entrance (Parcheggio Azienda Agricola Piscina Mirabile). OpenStreetMap maps surface car parks about 150 m from the cistern.

Before you go

  • Booking is compulsory and a helmet must be worn inside.
  • The ticket office lists the site as not accessible on one page and as only partly accessible on another; there are stairs down into the cistern.
  • The Campi Flegrei are volcanically active, and the park refunds tickets when a site has to close because of ground movement (bradyseism). Check before travelling.

Hours and prices checked 22 October 2026 on the operator's own site. Confirm before travelling.

The Aqua Augusta

The cistern was the end point of the Aqua Augusta, the aqueduct that also carried water to at least eight towns around the Bay of Naples (en.wikipedia). It drew on springs near Serino in the mountains near Avellino, at 376 m above sea level, and reached the Piscina Mirabilis after 96 km; with its ten branches it ran to about 145 km. It is attributed to Marcus Agrippa and dated to the reign of Augustus, between 33 and 12 BC (it.wikipedia). An inscription of AD 324, recording a restoration under Constantine, lists the towns it served: Nola, Acerrae, Atella, Naples, Pozzuoli, Baiae, Cumae and Misenum; Pompeii and Herculaneum had been supplied too before the eruption of AD 79 buried them (en.wikipedia).

Most of it runs underground and little of it can be seen. Visible stretches include the twin arcades of the Ponti Rossi in Naples, arches in the cellars of Via Arena alla Sanità that are open to the public, a section beside the Crypta Neapolitana, and, around Bacoli, a water-catchment cave near Scalandrone and a stretch next to the entrance of the Baia archaeological park (en.wikipedia).

History

The cistern was built under Augustus (en and it.wikipedia), or at the start of the 1st century AD (the ticket office). It is usually said to have supplied the Roman fleet based at Misenum (it, de and fr.wikipedia; the ticket office), but it lies about 1 km from the base’s quarters, which the aqueduct fed directly, so it may instead have belonged to one of the area’s great villas (en.wikipedia). A row of twelve small vaulted rooms was added along one side in the 1st or early 2nd century (en.wikipedia). The cistern went out of use for good when the Aqua Augusta was destroyed, between the 4th and 5th centuries (en.wikipedia).

In later centuries some of its waterproof plaster was scraped off to make gunpowder (de.wikipedia), and during the Second World War it served as an air-raid shelter (en.wikipedia). The name, “wondrous pool”, is credited to Petrarch in the 14th century (en and de.wikipedia), though the Italian and French articles date it to the 16th or 17th century. Excavation was completed between 1910 and 1926; the pillars were refaced in 1926, missing parts of the vaults were rebuilt in 1936, and the roof terrace was waterproofed in 2007 (en.wikipedia). Eighteenth-century travellers likened it to an underground cathedral, and it has become a favoured setting for performances and films (the ticket office).

More photographs

An 18th-century engraved floor plan of a long rectangle filled with a grid of cross-shaped piers, four rows of them, with hatched features at two corners and scale bars below.
The plan from the same book of 1768, with its four rows of cross-shaped piers. · Photo: Th. Rajola Arch, de. & Fiorolli, Sculp. · Public domain · Wikimedia Commons
A sepia photograph of a ruined arcade of brick and stone arches at the end of a tree-lined road, with a small figure standing under one arch.
The Ponti Rossi in Naples, arches of the Aqua Augusta, photographed by Giorgio Sommer. · Photo: Giorgio Sommer · Public domain · Wikimedia Commons

Nearby

  • A broad square courtyard paved with pale stone slabs, with a low round podium at its centre ringed by broken column stumps and, behind it, three tall plain columns; a wooden fence and grass in the foreground, and pastel apartment blocks above a brick boundary wall beyond.

    Photo: Superchilum · CC BY-SA 4.0 · Commons

    5 km · site · Campania

    Macellum of Pozzuoli

    The whole plan of the market lies open in a sunken square of about 58 by 75 m, a few steps from the harbour quays in the centre of Pozzuoli (the operator).

  • The oval floor of the arena, set with rows of rectangular openings covered by grilles, ringed by a low wall and by banks of stone seating overgrown with grass, with cypresses and modern buildings beyond.

    Photo: DimiTalen · CC0 · Commons

    5 km · city · Campania

    Puteoli – Pozzuoli

    The Flavian Amphitheatre is the set piece: only the Colosseum and the amphitheatre of Capua are larger.

  • Excavated walls and a straight paved street running across the lower city, with orange safety fencing round open trenches and a wooded hill rising behind, with structures on its crest.

    Photo: AlexanderVanLoon · CC BY-SA 3.0 · Commons

    6 km · city · Campania

    Cumae

    The visit centres on the acropolis, a hill above the coast with remains on two terraces (the operator).

Straight-line distances.

Sources

Every fact on this page comes from the records below, each used under the licence noted.

SourceLicence
Pleiades 812127750CC BY
Wikidata Q222410CC0
Vici.org 78062CC BY-SA (text), CC0 (metadata)
OpenStreetMap way/1241141330ODbL
Wikipedia (en) — Piscina MirabilisCC BY-SA 4.0
Wikipedia (it) — Piscina mirabilisCC BY-SA 4.0
Wikipedia (de) — Piscina mirabilisCC BY-SA 4.0
Wikipedia (fr) — Piscina mirabilisCC BY-SA 4.0
Wikipedia (en) — Aqua Augusta (Naples)CC BY-SA 4.0
Wikipedia (it) — Acquedotto romano del SerinoCC BY-SA 4.0
Pleiades — Aqua Augusta (Serino aqueduct)licence not recorded
Wikidata — Aqua Augusta (Q631734)licence not recorded
Parco Archeologico dei Campi Flegrei — visitor information (the operator)licence not recorded
CoopCulture — Piscina Mirabilis (the ticket office the operator links to)licence not recorded
CoopCulture — Piscina Mirabilis, accompanied entry for individuals (tickets)licence not recorded