This thesis examines the effects the imposition of Anglo-Norman lordship, following the Anglo-Norman expansion into Wales in the eleventh and twelfth centuries, had upon the landscape of the Welsh border region. In order to achieve this aim this project makes extensive use of digital Geographical Information Systems (GIS) in order to produce a detailed county-wide study of the landscape of post-Conquest Monmouthshire as well as comprehensive case studies of individual Anglo-Norman lordships contained within the boundaries of the county. This thesis also aims to locate its findings within important current debates in historic archaeology about the effects of medieval lordship upon the landscape, on the roles of the physical environment and human agency in the forming of the historic landscape, on the wider role of castles as lordship centres, beyond simple military functionality.