A detailed examination of the tenurial evidence and physical structure of the castles, moated sites and ditched enclosures of the Lancashire hundred of West Derby. Lewis examines the status and distribution of moated sites, changes in landuse before and after the Conquest and the social and economic context of the sites. An examination of the archaeological evidence for earthworks in the area is followed by a catalogue of over 50 townships and earthworks, each with at least one plan, and a summary of estate ownership.