Castelleone is located on the border with the province of Pesaro-Urbino. Situaded on a hill to the right of the Cesano River, this village is a renowned centre for nursery-gardening. The founding of the fortified settlement of Castillione is tied to the destruction of the Roman municipium of Suasa during the wars between the Greeks and Goths since the refugees took shelter on a nearby hill and re-founded their town. The church os San Francesco di Paola is located within the walls and houses a precious canvas by San Antonio Abate(17th cent.), corso Marconi is lined with semi-detached houses and, on the one side, with elegant porticoes. Along this road stands the parish church of Ss. Pietro e Paolo, from the mid 16th century.
The Archeological Museum “A. Casagrande” (about the Roman City of Suasa)is located in Palazzo Liva della Rovere (16th cent.) and displays the various finds from digs in the area, including a head of Augustus and frescoes from the domus patrizia. (Roman noble house). The murals, from the early 2nd cent. AD, reveal a close link to the wall decorations of the so-called style IV fromPompei and are arare example of late-imperial pictorial decoration in the Marche region.
About 2 km outside Castelleone, is the Pian Volpello area (Archeological Park area) where Suasa once stood. Excavations, dating from 1987, have brought to light the ancient flagstone road, the trading forum, small shops, some tombs, the domus and the amphitheatre. The domus is the main attraction of the archaeological park: the rediscovered mosaics are the most important unitary complex of the Marche region.
The “Festival of Forgiveness”, (the most important religious event of the year) is held in spring. The main event is undoubtedly the " the Onion Festival", on the first weekend of September, which involves touring shows and food stands with interesting and delicious recipes based on onions.