For some local historians, the town's name derives from the Latin "Castellum Leonis" (the symbol chosen as coats of arms by the Family that ruled the area for a long period of time), while for others, it would refer to the castle overlooking the village and the particular location of this near to the Trasimeno. Municipality in the province of Perugia, located on a promontory on the West bank of Lake Trasimeno, on the border with the provinces of Siena and Arezzo. The territories of the municipality also include the island of Polvese. The main centre features medieval characteristics with its ancient city walls and a plan based on three parallel streets and dominated by the castle on the nearby hilltop.
The area was originally inhabited by the Etruscans, followed by the colonization by the Romans, which were also the founders of the first settlement, taking advantage of its strategic location and giving it the name of Nuova Chiusi (New Chiusi). The Roman origins are clearly evidenced in the building basics of the urban structure. The village submitted the attack and destruction by the troops of Enrico IV in 1091 and was, later, rebuilt in 1247 and subsequently experienced a period of peace and development under the rule of Emperor Frederick II. During the medieval period, the town belonged to Perugia which imposed very strict statutes and proclaimed fief, it was ceded to the powerful Baglioni Family. Contended over the centuries by the cities of Florence and Perugia and the Papal States, finally, in the XVIII century, the town was incorporated between the territories, that belonged to the Church.
- the Church of the Magdalene, built in 1836 by the architect Caproni, features a Neoclassical façade and houses a valuable artwork depicting the Virgin and Child with Saints, a XVI century masterpiece of the artist Eusebio da San Giorgio, frescoes of the XIX century by Piervittori and a XIV century Madonna del Latte;
- the Church of San Domenico, built in the first half of the XVII century, in Baroque style and features a beautiful XVIII century coffered ceiling and several paintings of the XVII century;
- the XVI century Ducal Palace, located in the main square, which preserves inside a precious cycle of frescoes of extraordinary size of the late Renaissance period, that cover an exposing area of 1200 square meters;
- the Castle, situated in a strategic and panoramic position, was built in medieval times. Known as the Fortress of the Lion, because its structure presents several traces dedicated to the constellation Leo. It features a tall watchtower with a triangular base, four corner towers and crenellated walls with battlements. It is connected by a walkway to the ducal palace.