The Piscina Mirabilis (

Latin Latin ( or ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken by the Latins (Italic tribe), Latins in Latium (now known as Lazio), the lower Tiber area aroun ...

for "wondrous pool") is an

Ancient Roman In modern historiography, ancient Rome is the Roman people, Roman civilisation from the founding of Rome, founding of the Italian city of Rome in the 8th century BC to the Fall of the Western Roman Empire, collapse of the Western Roman Em ...

cistern A cistern (; , ; ) is a waterproof receptacle for holding liquids, usually water. Cisterns are often built to catch and store rainwater. To prevent leakage, the interior of the cistern is often lined with hydraulic plaster. Cisterns are disti ...

on the Bacoli hill at the western end of the

Gulf of Naples The Gulf of Naples (), also called the Bay of Naples, is a roughly 15-kilometer-wide (9.3 mi) gulf located along the south-western coast of Italy (Metropolitan City of Naples, Campania region). It opens to the west into the Mediterranean ...

, southern

Italy Italy, officially the Italian Republic, is a country in Southern Europe, Southern and Western Europe, Western Europe. It consists of Italian Peninsula, a peninsula that extends into the Mediterranean Sea, with the Alps on its northern land b ...

. It ranks as one of the largest ancient cisterns built by the ancient Romans, compared to the largest Roman reservoir, the Yerebatan Sarayi (''aka'' Basilica Cistern) in

Istanbul Istanbul is the List of largest cities and towns in Turkey, largest city in Turkey, constituting the country's economic, cultural, and historical heart. With Demographics of Istanbul, a population over , it is home to 18% of the Demographics ...

. The adjective ''Mirabilis'' was given by the 14th c. Tuscan poet Francesco Petrarca on one of his visits.

History

The Piscina Mirabilis was built under

Augustus Gaius Julius Caesar Augustus (born Gaius Octavius; 23 September 63 BC – 19 August AD 14), also known as Octavian (), was the founder of the Roman Empire, who reigned as the first Roman emperor from 27 BC until his death in A ...

possibly to provide water to the '' Classis Misenensis'' in the nearby port of

Misenum Miseno is one of the ''frazione, frazioni'' of the municipality of Bacoli in the Italy, Italian Province of Naples. Known in ancient Roman times as Misenum, it is the site of a great Roman port. Geography Nearby Cape Miseno marks the northw ...

, which needed large quantities of fresh water for the base itself and for the ships. As it lies 1 km away from the residential and military quarters at Misenum which lay beside each other and which were fed directly by the Aqua Augusta, it is also possible that the cistern belonged instead to one of the many luxurious villas built in this area, like the smaller Grotta della Dragonara and Cento Camerelle cisterns nearby. The Piscina Mirabilis was supplied with water from the Aqua Augusta, built after 33 BC, which brought water to most of the sites around

Naples Naples ( ; ; ) is the Regions of Italy, regional capital of Campania and the third-largest city of Italy, after Rome and Milan, with a population of 908,082 within the city's administrative limits as of 2025, while its Metropolitan City of N ...

. A row of twelve small chambers with barrel vaults were added on the north-eastern side in the late 1st to early 2nd century to increase the usable capacity and constructed in '' opus mixtum'' and '' opus vittatum''. In one of them is an '' opus signinum'' floor with labyrinth-shaped mosaic ''tesserae'' and a central white inlaid panel with limestone

polychrome Polychrome is the "practice of decorating architectural elements, sculpture, etc., in a variety of colors." The term is used to refer to certain styles of architecture, pottery, or sculpture in multiple colors. When looking at artworks and ...

tiles, which seems to date to a more ancient phase. The cistern was definitively out of use when the Aqua Augusta was destroyed between the 4th and 5th century AD.

Structure

Testament to its monumentality are the dimensions: high, long, and wide. The capacity is , amounting, in other words, to 12.6 million litres (3.33 million US gallons) of water, or roughly the size of 5 Olympic-size swimming pools. It was built as a kind of hypostyle hallDe Feo, Giovanni & De Gisi, Sabino & Malvano, Carmela & De Biase, O. (2010).
The Greatest Water Reservoirs in the Ancient Roman World and the “Piscina Mirabilis” in Misenum
'. Water Science & Technology: Water Supply. vol. 10, issue 3, pp 350–358. Publication by IWA Publishing, 2010. on a quadrangular plan to obtain four rows of twelve cruciform pillars per row which divide the interior space into five long naves and thirteen courtyards (just as if it were a

cathedral A cathedral is a church (building), church that contains the of a bishop, thus serving as the central church of a diocese, Annual conferences within Methodism, conference, or episcopate. Churches with the function of "cathedral" are usually s ...

, hence its local nicknames of "''the Water Cathedral''" or the "''Cathedral of Bacoli''"). The 48 columns support a barrel vaulted ceiling covered by a roof terrace made of '' opus caementicium'' and paved in waterproof '' opus signinum''. The ''piscina'' had two entrances (AA), a staircase supported by three arches in the north-west corner and one in the south-east, currently closed. The only one of the two staircases (CC) that still allows access to the main nave is the north-western staircase. Given the absence of holes visible from the outside, it is presumed that water was introduced through pipes coming from the North-West entrance (D). In the middle of the short central nave there is a 1.1 m deep basin (BB), hollowed out in the floor and provided with an outlet at one end, which served as a so-called ''piscina limaria'' (waste-bath, i.e. a settling and drainage basin) for the decantation, cleaning and periodic emptying of the cistern. Water was extracted from above through ancient hydraulic systems, exploiting the holes in the barrel vaults. The walls and pillars of the pool are faced in ''opus reticulatum'', with recourse to bricks for the walls and to ''tufelli'' for the pillars. A usual, the walls are waterproofed with ''opus insigninum'' (''cocciopesto'' in Italian), smoothing the corners through kerbs placed at their bases. Water was pumped out of the cistern using machines placed on the roof terrace of the cistern, which were extended in the 1st century AD by adding a series of 12 supporting barrel-vaulted rooms on the north-west side.

Restoration

The first work documented is the completion of the excavations between 1910 and 1926, followed by the consolidation of the damaged walls. In 1926 restoration of the second and third supporting arch was carried out and the surfaces of the pillars were restored with new ''opus reticulatum''. In 1929 the access staircase was covered with a layer of ''cocciopesto''. In 1936 the missing parts of the vaults were reconstructed and the extrados was repaired with concrete. In 2007 the roof terrace was consolidated and waterproofed.

Access

The ancient cistern is in private hands but is open to the public.

References

External links

Official site Piscina Mirabilis - BacoliOfficial Campania Tourism SiteOfficial Tourism Portal - Comune di Bacoli (Italian)
(Italian)

(Italian) *Archaeological Park of the Phlegraean Fields
Parco Archeologico Campi Flegrei (Italian)
{{Authority control Mirabilis Buildings and structures in Campania Mirabilis Tourist attractions in Campania Archaeological sites in Campania Bacoli Phlegraean Fields