The abbey, a Burgundian style church, was founded in 871 and then were promoted rebuilding works ended only in the late 12th century under abbot Leonate.
It was erected on an Roman temple and still today the old remains are well preserved. Abbot Leonate ordered the monk Giovanni di Berardo to collect and to reorganize all the documents in the abbey, with a precise chronicle of the abbey. The records represent the Chronicon Casauriense, held in the National Library in Paris.
For years the church remained abandoned, in poor conditions since at the end of the XIX century the poet Gabriele D'Annunzio promoted the safeguard the abbey, so in 1920 started the restoration works, thanks also to the committment of Pier Luigi Calore.
In 1894 the church was declared national monument. The configuration of the church is a nave and two aisles with semicircular apse and the entrance is imposing with beautiful bronze doors. Inside the church are a valuable paschal candelabrum and a massive ambo dating from the 11 hundreds, a fifteenth-century ciborium and the original early Christian sarcophagus, once it held the relics of St. Clemente.
It is possible to visit the Abbey Museum, next to the convent and the exhibition of gravestones and relics rediscovered during archeological excavations.