Caltanissetta

Caltanissetta (; ) is a "comune" in the central interior of Sicily, Italy, and the capital of the Province of Caltanissetta. Its inhabitants are called "Nisseni".
In 2017, the city had a population of 62,797. It is the 14th largest "comune" in Italy measured by area, the sixth highest "comune" in Italy by elevation (568 m), the second highest elevation in Sicily after the city of Enna (912 m).
Its patron saint is Archangel Michael.
Geography.
The town lies in an area of rolling hills with small villages and towns, crossed by the river Salso. It borders on the municipalities of Canicattì, Delia, Enna, Marianopoli, Mazzarino, Mussomeli, Naro, Petralia Sottana, Pietraperzia, San Cataldo, Santa Caterina Villarmosa, Serradifalco and Sommatino. Its "frazioni" are the villages of Bifaria, Borgo Petilia, Borgo Canicassè Casale, Cozzo di Naro, Favarella, Prestianni, Villaggio Santa Barbara, Santa Rita and Xirbi.
Territory.
Caltanissetta dominates the whole valley of the river Salso, which extends to include the nearby Enna. Morphologically it matches the surrounding area, very harsh and composed of limestone and clay. The city lies between three hills (Sant'Anna, Monte San Giuliano, and Poggio Sant'Elia), which form a basin which comprise part of the historical centre and South.
The "Maccalube" of Terrapellata.
The "Maccalube" (singular: "Maccaluba", from Arabic "maqlūbah", '(a land) that turns over', from the verb "qalaba" 'to turn over, to turn upside down, to invert') are a particularly rare phenomenon of sedimentary volcanism occurring in the Terrapellata area of Caltanissetta, the so-called Hill of the Volcanoes, near the village of Santa Barbara. This is an area of barren hills, with a colour ranging from white to dark grey, where mud volcanoes of around one meter in height rest on volcanic sediment.
The phenomenon is related to the presence of extensive underground clay deposits, interspersed with layers of salt water. 
Maccaluba is created by ejection of methane gas bubbles under pressure. 
When gas breaks through the clay deposits, it creates channels as it rises to the surface. These channels permit the clay sediment and water to travel, especially when they are pressured from beneath. 
The consistency of the soft clay and water 'sludge' erupting as a mixture then forms a clay cone on the surface, the top of which is similar in appearance to a volcanic crater. These formations remains soft for some time, unlike the igneous rock eruptions and cones often associated with volcanoes such as Mount Etna.
The Maccalube Emergency of August 2008.
On 20 August 2008 a State of Emergency was declared because of events involving the Santa Barbara district in Caltanissetta in the preceding days.
During the morning of August 11, 2008 geological instability caused the opening of rifts in the ground surface, varying from ten centimetres to a metre in diameter. Damage to buildings occurred in two areas up to distant, the Maccalube and in the western part of the City Centre.
These damages were made worse by an eruption of clay-mud, water and gas which occurred some hours later that same day. For seven minutes, a sizable eruption created a mud deposit thick and wide, across a large area.
On August 19, the first manifestations of further Maccalube eruptions appeared on top of the mud layer, where water and mud had been ejected by the previous eruption.
The Terrapelata phenomenon has been known for at least two centuries. 
The local Abbot, Salvatore Li Volsi (1797–1834), an expert in natural and agricultural sciences, wrote "Sul vulcano aereo di Terrapilata in Caltanissetta" ("Regarding the aerial volcano of Terrapelata in Caltanissetta"). He describes similar events which had occurred between 1783 and 1823, which he attributed to large-scale instability in the area. 
In recent decades these events have gradually become less violent, creating relatively inactive Maccalube, rather than violent eruptions and rifts in the terrain. 
As of September 2008: 68 craters out of 98 were said to be active; 17 were dormant; those remaining were thought to have solidified.
The events of August 11 are similar to those of February 14 and 15, 2002. Those of August were characteristic of a more severe eruption and of instability of the terrain beneath the populated area of the town. These events had, in the past, extended even further into the city area; but they had never before happened at the same time as eruptions.
History.
Caltanissetta's origins can be traced back to 406 BC, when admiral Nicia of Hamilcar's siege force from Carthage established a fort at the site, later called "Castra Nicia" (Fort Nicia).
After the Second Punic War, "Castra Nicia" came under Roman rule, but as in the rest of Sicily, the influence of the invaders remained superficial.
In AD 829, the city was occupied by the Saracens. The Carthaginian name, similar to the Arabic word "nisā’" (meaning 'women') resulted in the Saracen name "Qal‘at al-Nisā’" ('Fort of the Women'), since Italianized to "Caltanissetta". The settlement was captured by the Normans in 1086. A charter was granted to the town in accordance with Count Roger Borsa's vast plan for the urbanisation of Sicily, and the urban plan that is still in evidence today was laid out.
After the Norman occupation the city was under the rule of the Hohenstaufen, the Anjou and the Aragonese kings, who gave it the title of 'County'. It was here that Frederick II of Sicily was proclaimed king. The city was the seat of another Parliament which aimed to settle the disputes which had arisen during the reign of Frederick III (1355–1377).
In 1406 Caltanissetta became a fiefdom of the noble Spanish family Moncada, which already owned the Estate of Paternò, and subsequently the area fell into great decay. Construction of the Cathedral began in 1539, and, notably, in 1566 a bridge was built over the Salso River. In this period the city began to expand outside the walls, with creation of the new areas of "Santa Flavia", "San Rocco degli Zingari" and "San Francesco". These included the medieval village of Arab origin. The areas were separated by two roads which crossed roughly perpendicularly to a central square (now Piazza Garibaldi): the current Corso Vittorio Emanuele (west-east) and the Corso Umberto I (north-south).
On July 8, 1718 the city was assaulted by Piedmontese troops, causing large loss of life to the population. In 1787 Johann Wolfgang Goethe visited Caltanissetta.
In 1812, the Moncada seignory ended after a rule of 406 years, when the feudal constitution was abolished and Caltanissetta was turned into the 22nd Comarca of Sicily. In 1819 the city was declared to be the Capital of the province. However one year later it was sacked as a punishment for its loyalty to the House of Bourbon. In 1844 it was elevated to a Bishopric seat.
After many Nisseni had taken part in his Thousands deeds, Giuseppe Garibaldi entered the city, together with Cesare Abba and Alexandre Dumas, père. On October 22 of the same year a Plebiscite declared Caltanissetta to be part of the new Kingdom of Italy.
After the Unification of Italy the area experienced an economic boom, largely due to extensive mining of sulfur. The mining was accompanied by various misfortunes: on the 27th of April 1867 47 people died due to a fire-damp explosion in the "Trabonella" mine; 65 miners died on November 12, 1881 in "Gessolungo" mine because of an explosion; and another 51 died in 1911 in "Deliella" and "Trabonella" mines.
In 1875, however, the population rose up against the Prefect, who was subsequently fired. On April 8, 1878 the city was connected to a railway, ending the historical difficulties in reaching it. Three years later the King Umberto I visited Caltanissetta along with his wife Margherita of Savoy and his son Victor Emmanuel III.
During the Second World War, as part of the Allied landing in Sicily( in July 1943), Caltanissetta suffered several bombings during which 351 civilians were killed. On July 10, 1943 U.S. 3rd Infantry troops landed in Licata and 8 days later, on 18 July they entered and occupied the city. The U.S. 1st infantry landed in Gela some hours later and advanced toward Catania to meet the U.S 45th Infantry, which had landed near Scoglitti.
Economy.
Caltanissetta's economy remained heavily reliant on agriculture until the 19th century, when sulfur mining industry began 
extensively. 275 sulfur mines were created in the province, employing 32,000 workers. 
Fratelli Averna SpA, a firm in the city, produces the Amaro Averna, a liqueur sold throughout Italy and beyond.
Nevertheless, Caltanissetta has long been stricken by poverty, especially its West side.
Main sights.
The city's monuments include:
Caltanissetta has three museums: the Diocesan Museum; the Mineralogical Museum; the Regional Archeological Museum. The latter holds displays mostly from prehistoric times and includes finds from archeological digs conducted in the 1950s. These include vases and tools from the Bronze Age, and early Sicilian ceramics.
Sites in the neighbourhood of Caltanissetta include:
1407 saw the castle become the property of the Moncada family from Spain, and thus began the Castle's subsequent period of decline. Having been deemed unsuitable as a noble residence, it was used only for military functions. At the end of the 15th century, the castle dungeons were used as prisons. In 1567 a strong earthquake caused the collapse of the castle. Only the ruins of two towers, still visible today, remained standing.
Transport.
Caltanissetta is served by the A19 motorway Palermo-Catania, with an exit linking to the Town Centre via a highway. The town has two railway stations: Caltanissetta Centrale on the Caltanissetta-Agrigento line and Caltanissetta Xirbi, on the Palermo-Catania line.
Media.
Caltanissetta is also the site of a Short-wave transmitter, broadcasting RAI. (The Long-wave transmitter was shut down in 2002).
Sport.
Caltanissetta is home to the Nissa F.C. A.S.D.Nissa Football Club, now playing in the Prima Categoria/First Division, i.e. level seven of the Italian Football League. 
The city also hosts "Città di Caltanissetta" Tennis Tournament, part of the ATP Challenger Tour.