This volume presents a comprehensive archaeological and historical investigation of the transition from the ancient Roman settlement of Cereatae Marianae to the medieval monastic complex of Casamari. Adopting the stratigraphic methodology of the archaeology of architecture, the research analyzes the standing masonry, structural phases, and physical evidence to reconstruct the site's diachronic development from the 11th century through the mid-13th century. The study meticulously documents the chronological succession of the early Benedictine phases and the subsequent Cistercian construction periods, integrating material culture with indirect historical, epigraphic, and iconographic sources. Beyond structural evolution, the text explores the broader socio-economic, political, and territorial dynamics of the region, emphasizing the abbey's influence on medieval land management, agricultural innovation, and regional governance. Ultimately, the work provides a unified, interdisciplinary model that bridges classical antiquity and medieval monasticism, offering key insights for both historical understanding and the architectural conservation of the site.