The Arabs called it Djebel Utlamat (outstanding mountain), the Normans Mons Djebel (mountain-mountain), and the Sicilians Mungibeddu (beautiful mountain). The Venetian Pietro Bembo even referred to it as the unmarried mountain in his work De Aetna (1496) to express its uniqueness in the geomorphological context of Sicily. Mount Etna, with a circumference of 135 km, the legendary forge of the gods, is a very complex volcano formed by the accumulation and layering of eruptive material that has built up over hundreds of thousands of years. The lava flows, the enormous amounts of slag, gravel, sand, and ash that have been continuously expelled by the volcanic activity of this extraordinary thermodynamic machine, have created the visible mountain, which stands 3,325 meters high, through layer upon layer of deposition.