San Pietro ad Oratorium
In the lunette there is a precious fresco probably representing Saint Peter enthroned, today however greatly ruined. The two jambs of the portal, with protruding basis and capitels , have decorations and bas-reliefs of the Byzantine epoch. Right of the portal there is a rectangular frame with the whole figure of a saint in high relief, keeping a book in his hands. On the side you can read: S. VINCENZUS DIACUNUS; the writing is related perhaps to the donation of the church of San Pietro by Desiderius to the monastery of San Vincenzo al Volturno. Along the right side of the church there is a secondary portal whose jambs support two carved shelves with classical motives derived from the Benedictine tradition.
On the apsidal arch there is a large ensemble with Christ seated on a throne and blessing in the Greek manner, holding an open book in his left hand. Around there are the symbols of the four Gospel writers: the angel and the eagle on top, the lion and the bull at bottom. Following the curve of the arch there are in a row one after the other the 24 Lords of the Apocalypse, bearded and white-haired, and in the gesture of lifting their golden cups toward Christ. Of the apsidal frescoes only two groups of three saints each are left, each framed within an arcade supported by mullions.