Among the most beautiful medieval monuments in Abruzzo, the Benedictine Abbey of San Clemente in Casauria arose along the ancient route of the Via Claudio-Valeria. According to the Chronicon Casauriensis, a manuscript compiled around the second half of the 12th century by the monk Giovanni di Berardo, commissioned by Abbot Leonate, the foundation dates back to September 871. The choice of the site, near the Pescara river, between the Duchy of Spoleto to the North and the Duchy of Benevento to the South, in a favorable position for controlling an area that would undergo the process of fortification starting from the second half of the 10th century, is linked to strategic and political-military issues. The chronicle, in addition to describing the place, reports the main events experienced by the monastery: the initial dedication to the Holy Trinity; the subsequent translation of the relics of San Clemente from Rome granted by Pope Adrian II; the Saracen invasions that occurred between 915 and 920; the transition under papal jurisdiction; the arrival of the Normans and the restoration works of the complex between the 11th and 12th centuries commissioned by the Benedictine abbots Grimoaldo and Leonate. This succession of events highlights the political importance assumed by the Abbey of San Clemente in Casauria, comparable to that of other well-known monastic centers in central Italy, such as Montecassino, San Vincenzo al Volturno, Farfa, Subiaco. The facade of the church is preceded by a portico with three arches supported by columns with decorated capitals. Of the three entrance doors, the central bronze portal is of particular interest, decorated with 72 figurative panels and accompanied by a rich sculptural apparatus characterizing the lunette, the lintel, and the jambs: the bas-reliefs describe the foundation, the donation, and the history of the abbey in accordance with what is described in the Chronicon. The building has a plan articulated in three naves separated by ogival arches on pillars, leading to a raised transept with a single semicircular apse. The crypt is accessible thanks to two staircases located at the ends of the side naves. Of notable importance for the history of Abruzzo medieval art are the finely carved religious furnishings that stand out inside the church: the ambo and the Easter candle along the main nave and the ciborium that stands out at the back of the apse. It is also worth noting the presence of a marble reliquary containing the remains of San Clemente near the ciborium. At the Abbey of San Clemente in Casauria, it is possible to visit the Antiquarium dedicated to the intellectual Pier Luigi Calore, known for his research activities conducted in the Abruzzo region between the 19th and 20th centuries. Inside, remarkable archaeological and medieval artifacts are exhibited.