Rocca del Leone is an interesting irregular pentagonal structure, dominated by a triangular keep 39 metres high; at the corners, four towers fortify the crenellated walls. The fortress was erected by Emperor Frederick II of Swabia in the first decades of the 13th century, as an objective in the deployment of troops, on the remains of an older building, complete with a parish church, dedicated to Sts. Philip and James, of which only a few ruins remain. The real stronghold is the extreme appendix of the bulwark that encloses the small peninsula on Lake Trasimeno. It exercised a careful watch over the lake and surrounding lands, representing the last precautionary fortification.