This thesis evaluates man's physical imprint on the natural landscape of North Wales in the prehistoric period and considers what imprint remains from his activities. Man's imprint can be classed under four main headings, namely, that arising from domestic, ritual, economic and defensive activities. Such diverse activities afford opportunities to consider multiple features together, thereby illuminating coordinated action between regions and emerging tribal groups. The investigations have emphasised the importance of open coastal and estuarine landfalls, from the Neolithic period onwards, and routes leading inland from them, especially along river valleys. Settlements tended to form clusters along them, the research suggesting that the earliest small upland sites were probably of the Beaker period. Late Neolithic and Bronze Age ritual is well attested, but the research also reveals the ritual importance of watersheds and running water in these periods. Constructional skills developed rapidly, even to developing an architectural awareness. A consideration of structures from the Bronze and Iron Ages suggested guidelines for distinguishing between unexcavated, and therefore not otherwise dated, structures from these periods. Some buildings, together with some other factors, strongly suggest the practice of transhumance in North Wales from as early as the Neolithic; while the layout of some settlements, believed to be Iron Age, suggest the development of partible inheritance among families, with the consequent multiple sub-division of land.Research into the siting of hill-forts has revealed observational and defensive networks, both coastal and inland, including along some identifiable tribal boundaries. Some hill-forts are now seen to have been collecting points and storage depots for goods, temporarily held for onward transmission, or for longer periods for redistribution, perhaps for other tribes as well as for local groups. These investigations suggest that the North Wales landscape, excluding the effects of modem industry and mechanized farming, with their attendant land enclosures, had changed little since prehistoric times and the pattern of the ancient landscape can still be discerned.