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“Once hell, now a paradise”


by Fabrizio Fiorenzano


Among the forty or so volcanoes, big and small, in the Campi Flegrei area, the most important by far and surely the most captivating one is called Solfatara, situated in Pozzuoli at Naples’ gates. Its natural formation seems to trace back at least 4000 years and it is still defined today in the same way as it was in the legend: “The Hell’s Gate of the Ancient Romans.”


The volcano is situated in the middle of a very important archeological area, formed by the Cuma acropolis, the Flavian amphitheatre, the Serapide Temple and the imperial thermal baths. A hike to the Solfatara is an experience one shouldn’t miss.

Its roots are buried deep in the past for at one time it was one of the inevitable stops of the Grand Tour, the educative and leisure travel itinerary that from the eighteenth century upper-class Europeans undertook in Italy and France.

At the beginning of the nineteenth century the volcano Solfatara became a military structure also used as a training area for target shooting. The use of the area as a military facility extended over the years, and was also used as a setting for sanguinary duels.

Later on, in 1861, the site was bought by the De Luca brothers who turned it into a scientific research center.

In early 1900 a structure for a spa was created there. Thanks to the presence of  natural mud-baths it was possible to be cured via the  immersion into the mud, sulphureous waters and natural hot springs. We know about these activities due to the finding of an advertising leaflet from the time.

The volcanic area is very big, covering about 33 hectares but for safety reasons the part open to visitors is quite limited. The area is an extremely interesting natural oasis that features geological, faunal and botanical natural phenomena typical of a volcanic area.

You can visit Solfatara by yourself or  accompanied by one of the qualified guides.

It will be a special encounter with a wild mysterious nature, and the visitors will be amazed by two unusual and extraordinary phenomena: water vapor condensation and sound reverberation.

The former is attained by approaching a smoke-hole whilst holding a small flame. In doing so you’ll note that vapors appears gradually more intense.

Sound reverberation can be experienced by dropping a stone to the ground. You’ll be able to hear clearly a deep reverberation, similar to the feeling of standing on a huge underground cavity. The sound is actually created by the presence of many micro cavities in the ground, already very porous because of the smoke-hole gases.

The main tourist attractions within the site are the mud-bath, the Big Mouth (that is the main smoke-hole), and the mineral water well and the old hothouses (natural saunas).




The mud-bath is a pond full of mud surrounded by a safety wire mesh that helps to dissuade foolhardy people from getting too close.

Even from a distance you can feel the heat radiating from the hot mud. The chemical combination of sulphurous gas is presumed to be generated by vapors at some hundred meters underground, at a temperature that fluctuates between 170° and 250° Celsius.

The mud on the surface shows visible streaks which are actually bacteria colonies that can resist high temperatures and are very interesting from a scientific point of view.




It’s the main smoke-hole of Solfatara. Here the smell of the odorous gases can be disgusting, in particular hydrogen sulphide, which remind you of rotten eggs. The yellow and red colouration of the rocks is caused by the presence of various minerals such as realgar, cinnabar and orpiment.

The ancient Romans called the Big Mouth “Forum Vulcani” that means “The Dwelling of the Fire God.”

At the beginning of 1900 the German volcanologist Friedländer built a small volcanologist observatory whose ruins are still visible. The observatory was destroyed both by the constant telluric movements connected to the bradyseism in the Campi Flegrei and the opening of a smoke-hole.

Bradyseism is a slow vertical movement of the Earth’s surface. Throughout history Campi Flegrei has periodically experienced phases of both positive (the gradual uplift of the Earth’s surface) and negative (the descent of the Earth’s surface) bradyseism. Throughout the centuries these oscillations have varied Pozzuoli’s position compared to sea level by several meters. In particular between 1983 and 1984 the Pozzuoli area was deeply struck by violent manifestations that shocked the entire population. Most of the people had to leave their houses and still today, after all these years, it is very hard to return to normality.




Another ancient relic preserved within the Solfatara site is a stone cylindrical structure called “The Old Well.” Its construction dates back to the beginning of 1800, the purpose of which was to extract alum from the water approximately 10 meters underground.

Sulphurous water has always been well known as a miraculous cure for many ailments. In medieval times in the Campi Flegrei area there were about forty thermal springs one of which was in Solfatara. The thermal water of Solfatara,  among its various characteristics are a sour taste similar to lemon, was believed to cure nervous problems, eyesight, fevers, skin diseases, infertility and even ulcers.

Around 1870 a well-known chemist from Naples University, Professor Sebastiano de Luca, investigated the characteristics and biological proprieties of Solfatara’s water, finding that it was full of alum, sulphur oxides, calcium sulfate, magnesium and many others minerals.

Later on, in early 1900, the spa again became active using the mineral water and remained in use until the 1920s. The depth of the water-bearing layer that fuels the well varies with time and there are reasons to believe that these variations may be connected to the phases of bradyseism.




Finally there are the hothouses, that look to the visitor like two old caves. Actually, they are not that old, since they were constructed at the beginning of the nineteenth century and their linear and angular structure, covered with bricks, is evidence of latter architectural knowledge.

They were built for the purpose of being natural saunas exploiting the natural vapor emissions which were believed to be very healthy. People usually stayed inside the caves only for a few minutes, enough to produce a strong perspiration and to make them breath in the intense sulphurous vapors. Therefore the hothouses were believed to be an excellent cure for respiratory disease, skin disease and rheumatisms. Natural saunas have been used since ancient times and they were one of the attractions of Campi Flegrei.

They are still active today; once inside it’s impossible to stay for very long due to the suffocating heat.

Today Solfatara is a protected area always under close supervision by the Vesuvian Observatory of Naples.

Throughout the area are scattered various measuring devices to keep the levels of carbon dioxide and other gases under control.

Visitors are allowed to enter the scientific hall in Solfatara without charge. Various minerals extracted from the ground are displayed there and visitors are able to watch very interesting footage about the volcanic phenomena of the Pozzuoli area.

Solfatara is not only a place to visit briefly. To enjoy its natural beauty and its healthy air, there is a campsite available, “Camping Internazionale” that covers an area of 30,000 square meters within the nature park and is equipped with comfortable chalets and caravans surrounded by greenery where you can spend a few cheerful days.

Also available in the campsite there is a large swimming pool (180 square meters) in the middle of a wonderful lawn. It is equipped with sun beds, umbrellas and lifeguards.

We can conclude by saying that Solfatara is a perfect mixture of nature, scientific curiosity, history, well-being and relaxation. Those who decide to spend a few days there, upon leaving will be sure to return.