Etna represents a special "astenospheric window" caused by the process of lithospheric convergence between Africa and Eurasia and its structural evolution deeply linked to the geodynamics of the Mediterranean basin. With its 135 km of perimeter, it developed, changed, was destroyed, and reconstructed with several geological events that followed each other throughout many dozens of thousand years. The beginning of the fascinating history of this volcanic group dates back to the middle-lower Pleistocene: 570,000-600,000 years ago, when the first eruptions took place. At that time, the area where today we see the towns of Acicastello, Acitrezza, and Ficarazzi was covered by a large sea gulf interested by an intense underwater volcanic activity. A lot of time later, through long and linear eruptive fissures, large lava fields formed: today, these fields can be found in the terraces situated at various altitudes in the geographical area where the towns of Valcorrente, S. Maria di Licodia, Biancavilla, and Adrano are situated. Afterwards, a central-like volcanism action followed, leading to the formation of imposing volcanic structures known as Calanna, Zoccolaro, Trifoglietto, Vavalaci, Cuvigghiuni, Pirciata, Giannicola, Ellittico, Mongibello. Serra del Salifizio and Serra delle Concazze delimit the huge natural amphitheater of Bove Valley, characterized by its horseshoe shape (covering a surface area of over 37 square km). This fascinating and wild natural environment with its overhanging walls, the heads of ancient lava banks, rocky cliffs, magmatic formations, gullies, eruptive structures, and lava flows represents the geological evidence of the polygenesis of Etna. Variously disarticulated scoria-like blocks and fragments with a crest-like morphology and tapered depressions marking the channels along which the lava flows (aa lava); curled surface areas simulating festoons or formed by a thick plot of lava strings creating bizarre patterns (pahoehoe lava); variously disarticulated and piled slabs originating tumuli-shaped mountains or ridges; more or less regular flat slabs created by the immediate cooling of fluid lava suddenly raised by the action of big gas "bubbles" (pillow lava); often, on these formations, systems of lava flow enclosed in a basaltic cover form: in the latest period of the effusive activity, they empty giving origin to tubes, caves, and flowing galleries.