Pietraroja is the second comune by altitude (818 m above sea level) of the province; it is limited to north from the western side, oasis of natural protection, of mount Mutria (1,823 m) in the southern chain of the Matese mounts (Apennines), to the border with comune of Guardiaregia in the region Molise. Its territory constitutes the high valley of the river Titerno, surrounded to north from Mutria and from Santa Crocella pass. Between these last two, in the place named "Tre Valloni", are the sources of the Titerno whose waters join with those of the torrent named "Acqua Calda" and, coasting along the buttress of Mount Mutria, they go down in the plain of Cusano Mutri passing through a canyon, delimited to north from the rocky table named Civita of Cusano Mutri and to south Civita of Pietraroja.