The aim of this paper is to discuss some topics traditionally disregarded by the Spanish historiographical discourse due to the scarcity and heterogeneity of the archaeological data available. Luckily, in recent times the development of cost-effective, specific methodologies based on the combination of remote sensing techniques, GIS software and archaeological field survey has revolutionized the studies on the Roman military presence in northwest Iberia. Consequently, the existence of new, detailed archaeological data allows the development of more precise morphological and locational analyses for the study of Roman military sites. Thus, we can now delve into the ways in which the theoretical principles of the metatio castrorum were locally adapted. This work is just a mere approach to this issue through the review of three main aspects: morphology, defensive system and locational pattern.