The Foglia is the northernmost river of the Marche region of Italy. In ancient times it was known as Pisaurus, as it debouched into the Adriatic Sea at Pisaurum (modern Pesaro). It was also known as the Isaurus. The source of the river is west of Sestino in the province of Arezzo (which is in the Tuscany region of Italy) in the Appennino Umbro-Marchigiano mountains. It flows east through an extension of the province of Pesaro e Urbino and then back into Arezzo before forming the border between Arezzo and Pesaro e Urbino. The river then flows into the province of Pesaro e Urbino past Piandimeleto and curves northeast and flows past Sassocorvaro before curving east again.