The Apennine ridge, rising gradually from the eastern side, forms the main mountain group of the Park: Mount Falterona - Mount Falco. Along the southern slopes of the Falterona, at an altitude of 1358 m, an abundant spring called Capo d'Arno is considered the origin of the major Tuscan waterway. Further east is the Lago degli Idoli, the most important archaeological site of the Casentino. The massif is covered up on the top by the beech, which leaves space here and there to some clearing that houses rare strips of alpine vegetation. Not far away is the highest peak of the Park and the Romagna Apennines: Mount Falco. In the clearings near the summit you can find blueberry shrubs, also present in the undergrowth of the neighbouring beech forests, and the rare cranberry. On the arenaceous outcrops of the northern slope are concentrated many of the most precious floristic species of the Park, among which the narcissus flowered anemone, the Eugenia violet, and the gentian verna.