This is the first of a number of volumes describing the 1980-86 excavations at the early medieval Benedictine abbey of San Vincenzo al Volturno in central Italy. This volume gives a general introduction to this important project, a description of the archaeological remains, and then detailed accounts of the excavation of the Carolingian Crypt Church, the `South Church', the Refectory, the Garden Court and the Entrance Hall. Also included is a reappraisal of the cycle of paintings in the crypt in the light of the excavations.