The first high mountain stage and also the first mountaintop finish of giro d’Italia 2018, it is a 163 km going from Caltanissetta to the Observatory on Etna, an active stratovolcano on the east coast of Sicily. In the first half the wavy course running across Enna and Piazza Armerina is an introduction to the final climb: past Paternò a 25-km uphill section with increasing gradient. Past Ragalna the veritable climb (new) starts on a narrow road winding across parks and lava flows up to the Astrophysics Observatory, located with approx. 3 km to go. The finish line is by the Rifugio Sapienza (finish of several past stages), the mountain Observatory of Catania named after M.G.Fracastoro who directed it in the late 50s.