One of the many caverns beneath Naples.

Running beneath Naples and the surrounding area is an underground geothermal zone called the "Campi Flegrei" ("fiery fields"). This geothermal area runs generally from Mount Vesuvius beneath a wide area including Pompei, Herculaneum, Naples and over to Pozzuoli and the coastal Baia area. Geothermal power is electricity generated by utilizing naturally occurring geological heat sources. ... Campi Flegrei (Burning Fields) is a large volcanic area situated in the west area of Napoli, Italy. ... This article is about the mountain in Italy. ... Pompeii is not to be confused with the Roman general Pompey. ... Herculaneum (in modern Italian Ercolano) was an ancient Roman town, located in the territory of the current commune of Ercolano, in the Italian region of Campania. ... Country Italy Region Campania Province Naples (NA) Mayor Rosa Russo Jervolino Elevation 17 m Area 117 km² Population  - Total (as of December 31, 2004) 1,000,470  - Density 8,457/km² Time zone CET, UTC+1 Coordinates Gentilic Napoletani Dialing code 081 Postal code 80100 Patron Saint Januarius  - Day September... Pozzuoli (pop. ... Baia is a commune in the Suceava County, with a population of 6,793 (2002 census). ...

Over millennia, extreme geothermal pressure has helped form a strong, durable tuffaceous volcanic sandstone called tuff. Tuff (from the Italian "tufo") is a classification of 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. Welded tuff at Golden Gate in Yellowstone National Park Tuff (from the Italian tufo and pronounced tuf) is a type of rock consisting of consolidated volcanic ash ejected from vents during a volcanic eruption. ...

Tuff is strong and easily worked, making it an ideal building material. Tuff is mined through an access and removal shaft called the occhio di monte, ("eye of the mountain"). Through this 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 periods. The following is a list of monarchs of the Kingdom of Naples and Sicily: // Hauteville Counts of Sicily, 1071–1130 Roger I 1071–1101 Simon 1101–1105 Roger II 1105–1130 Hauteville Kings of Sicily, 1130–1198 Roger II 1130–1154 William I 1154–1166 William II 1166–1189 Tancred... The following is a list of monarchs of the Kingdom of Naples and Sicily: // Hauteville Counts of Sicily, 1071–1130 Roger I 1071–1101 Simon 1101–1105 Roger II 1105–1130 Hauteville Kings of Sicily, 1130–1198 Roger II 1130–1154 William I 1154–1166 William II 1166–1189 Tancred... The following is a list of monarchs of the Kingdom of Naples and Sicily: // Hauteville Counts of Sicily, 1071–1130 Roger I 1071–1101 Simon 1101–1105 Roger II 1105–1130 Hauteville Kings of Sicily, 1130–1198 Roger II 1130–1154 William I 1154–1166 William II 1166–1189 Tancred...

The resulting caverns were used to form water reservoirs into which water was diverted from the main aqueducts. The Greeks 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. A reservoir (French: réservoir) is an artificial lake created by flooding land behind a dam. ...

Over the centuries a massive honeycomb of caverns and passageways has been created beneath Naples and its environs. In World War II many of the quarry shafts were enlarged and spiraling stairways were added, opening up the caverns for use as air raid shelters. Combatants Major Allied powers: United Kingdom Soviet Union United States Republic of China and others Major Axis powers: Nazi Germany Italy Japan and others Commanders Winston Churchill Joseph Stalin Franklin Roosevelt Harry Truman Chiang Kai-Shek Adolf Hitler Benito Mussolini Hideki Tojo Casualties Military dead: 17,000,000 Civilian dead...

The resulting cavities beneath the city can now be divided up into several major categories:

1) Aqueducts and sewer tunnels;

2) Rainwater cisterns, reservoirs and aqueduct diversionary channels;

3) Caverns left from quarrying of tuff;

4) Other voids from removal of sand and other types of materials;

5) Interconnecting tunnels and passageways among caverns;

6) Places of worship, including catacombs and pre-Christian hypogea;

7) 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 (cult burial chambers) and many ancient artifacts discovered during more than half a century of exploration. The Holy of Holies, Hypogeum, Malta The Hypogeum in Hal-Saflieni, Paola, Malta, is an subterranean structure excavated c. ...

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. ISBN: 8851001316

Piedimonte, Antonio E. The other city. English translation

Salvi, Fulvio. Breve Storia del Sottosuolo di Napoli. [1]

External links

• One of a number of video clips on You Tube of the caverns beneath Naples. Voice overdub is in Italian.
• Homepage for Napoli Underground
• Article from Around Naples Encyclopedia