Castignano is a comune (municipality) in the Province of Ascoli Piceno in the Italian region Marche, located about 80 km south of Ancona and about 10 km northeast of Ascoli Piceno. Castignano borders the following municipalities: Appignano del Tronto, Ascoli Piceno, Cossignano, Montalto delle Marche, Montedinove, Offida, Rotella. Among its churches are the Sanctuary of San Bernardino da Siena and Santi Pietro e Paolo. Its territory is home to the oldest ever Italic language inscription found, the so-called "Stele of Castignano" (7th-6th centuries BC).