The abbey was founded in 871 by Louis II, great-grandson of Charlemagne, after a vow made during his imprisonment in the Duchy of Benevento.
In its history the abbey was plundered several times: by the Saracens in 920 and repeatedly by the Norman count Malmozzetto between 1076 and 1097.
The façade is preceded by a portico with columns and capitals; under it are three portals, the middle and larger one having a lintel and a tympanum with sculpted stories of St. Clement and of the abbey's history.
In the center of the tympanum is the figure of San Clemente in his Papal clothing, with Saints Fabio and Cornelius at his right side and Abbot Leonate, to his left, presenting a model of the rebuilt abbey to its patron.
Inside the (now deconsecrated) church there are a beautiful paschal candelabrum and a massive ambo dating from the 11 hundreds.