Founded by Benedict Biscop in the late 7th century, the twin monastery of Wearmouth and Jarrow achieved an international reputation through the writings of Bede. Destroyed in the mid 9th century the house was refounded in the 11th and survives to this day as a seat of religious scholarship. This report describes the excavations undertaken at the two sites by Rosemary Cramp between 1959 and 1988. They showed that the founder did indeed build in stone "in the Roman manner" as the early texts describe, and they provide important evidence into the evolution of monastic plans at this early period. The finds indicate the economic and the international contacts maintained by the monastery, including exotic pottery, and the greatest quantity of 7th and 8th century coloured window glass from any comparable site. From the later monasteries the evidence demonstrates the changing local and regional economies, and the cemeteries provide long-term demographic evidence. This first volume provides an authoritative study of the fabric and strctures of these two establishments; a second volume will describe the finds and their contexts.