Running beneath the Italian city of

Naples Naples (; it, Napoli ; nap, Napule ), from grc, Νεάπολις, Neápolis, lit=new city. is the regional capital of Campania and the third-largest city of Italy, after Rome and Milan, with a population of 909,048 within the city's adminis ...

and the surrounding area is an underground geothermal zone and several tunnels dug during the ages. This geothermal area is present generally from Mount Vesuvius beneath a wide area including

Pompei Pompei (; nap, Pumpeje, ) or Pompeii (, as in the name of the ancient city) is a city and commune in the Metropolitan City of Naples, Italy, home of the ancient Roman ruins of Pompeii that are part of the UNESCO World Heritage Sites. History ...

Herculaneum Herculaneum (; Neapolitan and it, Ercolano) was an ancient town, located in the modern-day ''comune'' of Ercolano, Campania, Italy. Herculaneum was buried under volcanic ash and pumice in the eruption of Mount Vesuvius in AD 79. Like the nea ...

, and from the volcanic area of Campi Flegrei beneath

and over to

Pozzuoli Pozzuoli (; ; ) is a city and ''comune'' of the Metropolitan City of Naples, in the Italian region of Campania. It is the main city of the Phlegrean Peninsula. History Pozzuoli began as the Greek colony of ''Dicaearchia'' ( el, Δικα� ...

and the coastal Baia area. Mining and various infrastructure projects during several millennia have formed extensive caves and underground structures in the zone.

Geology

Over millennia, extreme geothermal pressure has helped form a strong, durable tuffaceous volcanic sandstone called

tuff Tuff is a type of rock made of volcanic ash ejected from a vent during a volcanic eruption. Following ejection and deposition, the ash is lithified into a solid rock. Rock that contains greater than 75% ash is considered tuff, while rock cont ...

, a rock composed of compressed and compacted volcanic ash ejected during a volcanic eruption. The entire Naples area is a geothermal region with deep veins of the tuff sandstone, generically referred to as "yellow tuff". It runs in deep veins beneath Naples and the area around it in strata which are found at different depths.

Mining and subterranean structures

Tuff is strong and easily worked, making it an ideal building material. Tuff was mined through access and removal shafts called the ''occhio di monte'', ("eye of the mountain"). Through these shaft, gigantic blocks of tuff were quarried and pulled up. The resulting void was a bottle shaped cavity with sloping shoulders, which provided ample reinforcement to prevent future cave-ins. After the tuff was quarried it was used as building material during roughly the Angevin, Aragonese and

Bourbon Bourbon may refer to: Food and drink * Bourbon whiskey, an American whiskey made using a corn-based mash * Bourbon barrel aged beer, a type of beer aged in bourbon barrels * Bourbon biscuit, a chocolate sandwich biscuit * A beer produced by Bras ...

periods. The resulting caverns were later used to form water reservoirs into which water was diverted from the main aqueducts, and the

Ancient Greeks Ancient Greece ( el, Ἑλλάς, Hellás) was a northeastern Mediterranean civilization, existing from the Greek Dark Ages of the 12th–9th centuries BC to the end of classical antiquity ( AD 600), that comprised a loose collection of cultu ...

dug long and elaborate aqueducts beneath the city more than 2,500 years ago. These provided fresh water to the villas and palaces above through use of the deep reservoirs and cisterns. Well shafts were also dug offering community access to the reservoirs below. Tuff tunnel below Naples

Over the centuries a massive honeycomb of caverns and passageways has been created beneath Naples and its environs. In

World War II World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposin ...

, many of the quarry shafts were enlarged and spiraling stairways were added, opening up the caverns for use as air raid shelters. The resulting cavities beneath the city can now be divided up into several major categories: * Aqueducts and sewer tunnels; * Rainwater

cistern A cistern (Middle English ', from Latin ', from ', "box", from Greek ', "basket") is a waterproof receptacle for holding liquids, usually water. Cisterns are often built to catch and store rainwater. Cisterns are distinguished from wells by t ...

s, reservoirs and aqueduct diversionary channels; * Caverns left from quarrying of tuff; * The remains of

Nero Nero Claudius Caesar Augustus Germanicus ( ; born Lucius Domitius Ahenobarbus; 15 December AD 37 – 9 June AD 68), was the fifth Roman emperor and final emperor of the Julio-Claudian dynasty, reigning from AD 54 un ...

's "lost" theatre; * Greco-Roman businesses, such as the remains of an ancient forum that was preserved in a mud slide; * Other voids from removal of sand and other types of materials; * Interconnecting tunnels and passageways among caverns; * Places of worship, including

catacomb Catacombs are man-made subterranean passageways for religious practice. Any chamber used as a burial place is a catacomb, although the word is most commonly associated with the Roman Empire. Etymology and history The first place to be referred ...

s and pre-Christian

hypogea A hypogeum or hypogaeum (plural hypogea or hypogaea, pronounced ; literally meaning "underground", from Greek ''hypo'' (under) and ''ghê'' (earth)) is an underground temple or tomb. Hypogea will often contain niches for cremated human rema ...

(cult burial chambers); * Major ancient and modern roadway tunnels, and rail and subway tunnels. Today, tours of the elaborate underground beneath Naples are available and there is even a museum of the underground located beneath Piazza Cavour in a huge quarry cavity with connecting tunnels and aqueduct passageways. It contains elaborate replicas of Greek hypogea and many ancient artifacts discovered during more than half a century of exploration. File:Naples Italy underground 5.jpg, Underground water duct File:Naples Italy underground passage 2.jpg, Underground well hole File:Naples Italy underground 4.jpg, Naples underground File:Naples Italy underground passage.jpg, Naples underground passage

References

*Milia A., ''et al.'' . (2006) "Rapid changes of the accommodation space in the Late Quaternary succession of Naples Bay, Italy: the influence of volcanism and tectonics" in monograph: ''Volcanism in the Campania Plain, Vesuvius, Campi Flegrei and Ignimbrites''. De Vivo: Napoli. *Piedimonte, Antonio E. (2003) ''Il cimitero delle Fontanelle. Il culto delle anime del purgatorio e il sottosuolo di Napoli''. Electa: Napoli. *Piedimonte, Antonio E
''The other city.''
*Salvi, Fulvio
''Breve Storia del Sottosuolo di Napoli''

External links

One of a number of video clips
on YouTube of the caverns beneath Naples. Voice overdub is in Italian.
Naples Underground Tour Homepage for Napoli Underground
{{Man-made and man-related Subterranea Volcanism of Italy Campanian volcanic arc Geography of Naples Mount Vesuvius Subterranea (geography) Archaeological sites in Naples