Smerillo is a comune (municipality) in the Province of Fermo in the Italian region Marche, located about 80 kilometres (50 mi) south of Ancona, about 35 kilometres (22 mi) northwest of Ascoli Piceno and about 35 kilometres (22 mi) west of Fermo, on a spur midway from the Monti Sibillini and the Adriatic Sea.It houses several remains of the medieval castle and walls. Also notable are the churches of Santa Caterina and San Ruffino.