A small hill town on the right of the Apsa torrent, close to the road which runs along the right bank of the Foglia valley from Pesaro to Gallo and on up to Urbino.
The Church of "Sancto Martini in Petriano" is mentioned in a parchment of 1069. The building still survives, built with three naves, truss beam roof (rebuilt during a later period) and adjoining bell tower. Here there is a venerated painting of "Our Lady of Lightening", protector of atmospheric events.