 On the southeastern side of Campo Imperatore are medieval hill towns once ruled by the Medicis, Castel Del Monte and Santo Stefano di Sessanio as well as the ruin of one of Europe's highest fortresses, Rocca Calascio.In spring, summer and fall, shepherds from these neighboring hill towns maintain herds of sheep, "semi-wild" horses, and cattle in the plateau.The pastures are covered with field grasses and meadowland wild flowers.