From Santo Stefano di Sessanio (1,251m) take on foot the road leading to Campo Imperatore. After a few hundred meters (trail marker), turn right and take a road and then a trail crossing a plateau and then climbing along a deep valley (Val Pareta) until you reach a road cut in the mountainside.
Follow it on the right, keep right when you reach a junction, and climb to the Renaissance oratory of Madonna dei Monti and to the fortress of Rocca Calascio (1,460m, 1 hour). You can also get here without taking a trail but with a visible route, following the ridge and going beyond Monte delle Croci.