This thesis is an examination of the archaeological, historical and landscape contexts of the Norman castle in the northern counties of Cumberland, Durham, Lancashire, Northumberland, Westmorland and the Ridings of Yorkshire. The assumption at the heart of this study is that castles are social institutions, arenas in which repetitive social actions, such as administration, are undertaken. Castles are also arenas where other forms of social interaction, such as warfare or sieges, were staged. These social actions, and the spaces in which they happened, structure and are structured by the ideas and concepts of lordship and actively employ castles in a meaningful way. It is demonstrated in this study that both architectural and landscape forms are actively employed in meaningful ways. What is emphasised and argued throughout this study is that evidence traditionally employed to provide chronological data, documentary evidence or architectural features, actually provide social information. This study also shows that the concept of lordship changes and develops over the late eleventh and twelfth centuries. These changes have consequences for the landscape context of sites where there are changing, developing relationships between settlements, whether newly founded or pre-existing, over time. The general conclusions reached in this study are that castles must be examined as social institutions rather than in isolation as architecture or simply as arenas where historical events took place. (Durham Univesity Abstract)