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Naples is seated on a bank of volcanic material; it has always been provided with a only few local water sources and so it has never been self-sufficient in water, but has always been forced to seek for it in an ever growing quantity somewhere else. So, the city was furnished with aqueducts ever since the ancient times.

The three main aqueducts that in the past supplied Naples with fresh water run mainly underground:

  • the Bolla Aqueduct is the first aqueduct for Naples built in ancient times (around 400 BC); it and has provided the city with drinking water for over two millennia!
  • the Serino Aqueduct originally built around 30 – 20 BC. It was known also as Augustus Aqueduct as it was constructed in Augustus era, and later as ClaudiusAqueduct, named after his renovator in the 4th century AD.
  • the more recent Carmignano Aqueduct, constructed during the Spanish vice royalty of 1600s.

The three aqueducts which cross over have resulted in a complex network of underground passageways and cisterns. All the buildings built up to the year 1885 (the year of a plague) are in one way or another connected to the cisterns. By that time, the building of the safer pressure aqueduct, which superseded all the running aqueducts, had already begun.

Amazingly, the ancient Bolla Aqueduct (with its later additions and reservoirs) was in use up until the late 19th century together with the Carmignano one, the latter intended mainly for mill work. In contrast, the Serino Aqueduct followed a different route along the coast and was dismissed by the 6th century because the Volcano activity had completely changed the orography of the site, creating even a new mountain (“Monte Nuovo”). Besides Neapolis, Serino supplied with fresh water Miseno, the harbour of the Roman war fleet and also the very rich towns of Pompei, Puteoli, Cumae, Baiae and Hercolaneum.

Serino picked up its waters much farther than Bolla, from the Apennines in Serino locality, about 80 km away from Naples, and its ling 100 km route ended in Bacoli in the grand Roman military fleet’s cistern known as Piscina Mirabilis.

In the 1600s, the viceroy prohibition of bringing building materials from outside the town that was growing too fast actually facilitated the tuff extraction. The Neapolitans went on building dwellings and palaces by using the tuff extracted from the subsoil leaving large caves eventually used for storing water. The underground reservoirs are in fact the most peculiar feature of Naples ancient aqueducts. 

The Bolla Aqueduct

Bolla is the oldest aqueduct of Naples dating back to the ancient times (around 400 BC). It was furnished by several water sources, lying ~ 10 km east of the ancient town, an area known as “Volla” plain. It is constituted by an 2,100 hectares wide strip of plain land facing the sea, in the shape of a fan and a very low slope (the highest point measures only 24m above sea level).

The site’s morphology and the presence along the seaside of sandy dunes which stopped the water flowing, favoured the stagnation of the area, which has always been presenting swampy characteristics and great water richness, both as above-ground and underground flows.

The ancient Volla plain also fed the ancient Sebeto River which flowed inside ancient Naples. By the 17th century the river had already disappeared and in art work it was represented as a human feature.   

From a functional point of view the Bolla aqueduct is divided in three sections, the first constituted by the draining tunnels admitted directly in the subterranean water flow, the second by the main channel to the city from the Water House to the Capuan Gate, (partially covered and partially open); the third by the dense distribution channels net dug in tufa.

The Bolla originated from the “Monte Somma”, 19 m above sea level. It drained underground channels and was divided in two branches, “Volla”, for the mills function and “Formale“ or “Formello” that after a route of about 8 km reached the town, near Formiello Fountain, a bit north of Capuan Gate at about 13 m above sea level. Inside the town the ancient branches are surely constituted by the Main branch and the Arch branch with their main secondary branches.

                    Image courtesy of Hydria Virtual Museum
Formiello fountain where Bolla entered Naples city

Hydria Virtual Museum

Bolla has been used mainly for domestic purposes, as its low height (13m above sea level at Capuana Gate) made it unsuitable for industrial exploitation. Moreover, Bolla’s original water source, which kept feeding it for centuries, was considered of a quality certainly superior than the other local sources and than the waters of the subsequent Carmignano aqueduct, built in the 17th century.

Estimating the water supply of Bolla, that in any case changed over times and along its route is not a simple task. Vermeau in late 19th century estimated Bolla’s flow at its arrival to town being 14.000 m3 per day; Firrao instead in 1966 estimated its arrival at the Capuan Gate at 5.198 m3 per day; while Ruocco in 1969 estimated the flow at its beginning at 43.000 m3 a day (500 lt per second).

The Bolla Aqueduct kept growing underneath the city for centuries. The lack of documents does not certify the aqueduct branches dating, but it can approximately be ascribed to the periods of urban expansion of the city.

Bolla developed also during the Angevin period (13th century AD) with the branch of S. Giovanni a Carbonara. All the buildings in the lower part of the city, at the foot of Vomero hill, received water via a narrow net of modestly inclined channels excavated in tuff that run along or under the streets depending on the period, while the upper districts always suffered water shortage. Those channels fed some underground tanks, connected to the surface through wells dug in the courtyards of buildings or directly inside the flats.

The knowledge of the aqueducts legal and abusive deliveries was fundamental for the city administration, who also charged technicians with the aqueduct’ maintenance. These “pozzari” (= shaft men, wellers) were the only real experts about the water tunnels, they knew the complicated network very well, where they moved with ease and familiarity. Actually the city under siege was twice conquered, in 536 and in 1642 AD, due to betrayal of pozzari who indicated the route to the invaders.

Since the 15th century several engineers have been periodically charged by the city’s governments with drafting its state of conservation and usage. In his report of 1884, Engineer Melisurgo, after personally inspecting the underground aqueduct, described the network made by irregular channels at variable sections, never going in straight line for more than 10 metres. Although it was impossible to design a complete map of the network, he noted that if someone could draw a section of the Naples subsoil to a depth of 12 m, the Bolla aqueduct would appear as a huge trunk with numerous big branches dividing, multiplying and crossing each other in a myriad of twists, as well as smaller straight parts, ending, in one case or another, in a tank and a well.

To satisfy Naples’ chronic need of water, in particular for industrial use, a new addition to Bolla was built in 1629 by Cesare Carmignano, owner of water mills. Both Bolla and Carmignano were partly open, which unfortunately produced a lot of defiling of the waters and epidemics.

With the construction of the contemporary pressure Serino aqueduct in the late 19thcentury the service of Bolla aqueduct seemed reach an end after two millennia! Still, in the 1930s some Neapolitan industries recovered its waters, and thanks to the restoration of one of its channels, Bolla serviced some industrial uses for Neapolitan hinterland.

Up until 6 decades ago, one could still move along kilometres of channel underground networks. During the World War II the tanks were turned into air-raid shelters. Also, huge amounts of rubbish and debris from collapsed bombarded buildings were thrown into the old aqueduct. It is estimated that only the 30% of the network is currently accessible, while the remaining part remains unknown.

The Serino or Aqua Augusta Aqueduct

The Roman aqueduct “Aqua Augusta” was originally built around the time of Augustus (30 – 20 BC). It is also known as “Claudius”, under whose empire it was restored in the 4th century AD (see more about the tablet announcing its restoration in PEOPLE / CULTURE), as well as “Serino” by the name of its sources.

It may not well known as other grandiose Roman Aqueducts, probably because it was mostly underground, with no remains of spectacular arched bridges. Even so, with a 100 km length it is a significant piece of engineering.

As Naples evolved from a Greek colony to a Roman and later imperial city after its acquisition, its water needs greatly increased. The Romans ensured additional water via the Aqua Augusta to complement to the existing Bolla one.

The extensive Roman aqueduct reached the port to supply the idle rich, the merchants and the imperial sailors with water. Its source was in the Terminio-Tuoro Mountains and was named the Fons Augusteus, not far from the city of Avellino.

Along its 100 km (!) length to service Miseno, the Serino aqueduct passed by eight cities including Pompeii, Herculaneum and Naples, with numerous branches that provided water to the existing public and private fountains and cisterns.

In Naples, the Serino line passed through a tunnel now known as the “Crypta Napolitana,” passing beneath the Posillipo hill to the Campi Flegrei, the town of Puteoli and finally the largest freshwater cistern ever built by the Romans, the Piscina Mirabilis at Miseno.

The total relief of the aqueduct is 366m from the source to the Piscina Mirabilis at 10m altitude, which gives a mean slope of 0,3%. The slope varied considerably, though.

                    Image courtesy of Hydria Virtual Museum
Longitudinal section of the Serino aqueduct above ground (top) and underground (bottom) © S. Piras, www.romanaqueducts.info

Hydria Virtual Museum

The long Serino Aqueduct always had a very troubled life probably because of the Vesuvius eruptions and of the subsequent earthquakes. It had first to be restored under Claudius in the 4th century and afterwards it was definitively dismissed around the 5th – 6th century. At the time, the city was serviced by wells and many smaller springs such as “Tre Cannoli”, “Acqua Aquilia”, ”Santa Lucia”, “Leone”, “San Paolo” and so forth.

The Carmignano Aqueduct of the 1600s

During the vice royal times (16th and 17th century AD) Naples had an extraordinary growth, and the water deliveries and picking ups along the aqueduct became innumerable, both inside and outside the urban territory, both legal and abusive. Water was used by the fountains, the merchants, religious orders, noble families and rich bourgeoisie. For the majority of population the most common source of water were the scattered public wells ranging from 3.700 up to 9.000 (!) according to some sources.

Therefore, in this period the problem of the Bolla’s insufficient water carriage became more and more drastic aggravated by the fact that part of its sources were channelled to the mills. Indeed, the need for an added supply or a new aqueduct became critical.

In the 16th century two new sources for Bolla were discovered near the two farmhouses, “La Preziosa” and “Tavernanova”. Later, other channels were connected to increase its supply. This addition to Bolla made in the 1600s was engineered by Cesare Carmignano, and named after him.

The new Serino aqueduct of 1882

Only in late 19th century after unification of Italy, as in many other European cities, the new technologies made it possible to construct the first pressure aqueduct for Naples. The new Serino aqueduct of 1882 replaced the two previous ones (Bolla and Carmignano). Actually, after more than 2000 years the long service of Bolla aqueduct came to an end.

Back in 1885 one could climb down one of the 4628 then known wells and tour the underground city in all its length and width from Santa Caterina a Formiello to Monte di Dio, from Ponti Rossi to Capo Misero, and from San Giovanni a Carbonara to the Sanità. 

Other waterworks around Naples

The Serino aqueduct filled several cisterns in the section beyond Naples. In Puzzuoli, the aqueduct served several cisterns, notably the Piscina Cardito (55x16m) from the 2nd century AD, and the Piscina Lusciano (35x20m) from the 1st century AD. Below two impressive waterworks at Miseno, the Piscina Mirabilis and the Cento Camarele are described. 

Piscina Mirabilis

The huge cistern was dug entirely out of the tuff cliff. Being 15 meters high/deep, 72 meters long, and 25 meters wide, having a capacity of 12,000m3, Piscina mirabilis is maybe the most impressive Roman cistern ever brought to light. It was supported by vaulted ceilings and 48 pillars lined in 4 rows, almost forming the aisles of a huge underground cathedral. It is entered by two staircases, diagonally opposite one another.

                    Image courtesy of Hydria Virtual Museum
Floor plan of the huge Piscina Mirabilis

Hydria Virtual Museum

The walls and pillars – built in opus reticulatum with brick appeals (side walls) and tuff (pillars) – have a typical waterproofing coating in earthenware often. At the base of the pillars and walls, the curb, smoothing the corners, had the function to prevent leaking. In the floor of the central nave is a basin of 1.10m depth which presumably served as a settling tank and drain for the cleaning and the ordinary emptying of the cistern. Near the entrance is the inlet conduit that permitted recharge. The absence of exit holes suggests that the water was extracted from the top by means of hydraulic machines and then channelled.

Piscina Mirabilis was mainly used to cover the needs of the imperial fleet at Miseno.

After a recent restoration today (2013) the site is open to public. It is actually frequently visited by photographers training studios, for practice, as the mould combined with the dim light on the pillars creates high quality scenery.

Cento Camarelle

Adjacent to the main cistern at Miseno were a number of other private cisterns such as the one today called Cento Camarelle (= 100 small rooms) a group of cisterns arranged on two levels built in different eras, between the late Republican age and the 1st century AD.

It is a structured set of water cisterns, used for the supply of the ancient villa on the sea orator Quintus Hortensius Ortalo. It was traditionally known also as “Nero’s Prisons”.

The complex is made by two independent floors, built on a tuff crag overhanging the sea. The oldest part occupies the lower floor and has a series of vaulted tunnels and a long corridor, leading to a suggestive sea view. The second floor, set 6 meters higher, has been realised only later. In fact, it presents a totally different position and it is made up by a big cistern divided into four naves by pillars that support the barrel vaults.

With the advent of Augustus and the construction of the port of Misenum, the whole of Centum Cellae underwent major transformations, adapted to deposit oil amphorae and vinarie or otherwise used as a store room to the fleet at Misenum.

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