Spoleto is located at the southern end of the Valle Umbra, a vast alluvial plain generated in prehistoric times by the presence of a vast lake, Illacus Umber, permanently drained in the Middle Ages, after its swamping, with reclamation works. The city developed on the Sant’Elia hill, a low hilly promontory at the foot of Monteluco, and further down to the banks of the Tessino stream; to the east is surrounded by the mountains that surround the Valnerina. Today it is a city of world-renowned culture with the well-established annual event of the Festival dei Due Mondi.