It is the largest doline of Gessi Bolognesi (with a diameter of over 700m) and includes minor dolines and several swallow holes, giving access to as many caves. Large woodlands cover the bottom and the coolest slopes, where several microthermal species stand out, including the one and only regional station of Isopyrum thalictroides. Meadows, cultivated fields, and a thin Downy oak woodland interrupted by the outcrops cover the sunniest areas. In winter, one of the paths is characterized by the rare crocuses. Discovered in 1932, Spipola Cave is exclusively accessible with guided visits from an artificial entrance situated at the bottom of the doline (the natural entrance, called “Buco del Calzolaio”, is situated immediately above it).