Iberian Copper Age «ditched» and «walled» enclosure sites are often thought to represent two clearly distinguishable groups of sites. However, the discovery of sites where both ditches and walls are present («mixed sites») complicates things. There are good reasons to question whether the aforementioned dichotomy is real, or if, instead, it is largely an artifact of research, resulting from a combination of poorly preserved archaeological contexts and inadequate survey strategies and methods which missed the potential integration of both building techniques at the same sites. This paper will address this problem from a Pan-Iberian perspective, as we will compare type-sites across multiple Iberian regions. We shall formulate and test seven relevant hypotheses by undertaking multiple comparative analyses at various scales on top of a purpose-built database including 345 sites. Among others, we will address questions such as: How frequent or rare are mixed sites? Is the perceived duality of the archaeological record (ditched versus walled) a by-product of preservation issues or the differential availability of certain building materials? Did walled and ditched enclosures really coexist in space and time? We conclude that: (a) Chalcolithic Iberian enclosures are markedly dichotomous (ditched vs walled); (b) «mixed» sites are rare exceptions rather than the rule; (c) walled and ditched enclosures show important differences in key features (topographic setting, geographical distribution); (d) such differences cannot be solely attributed to geological factors. The paper will end with a discussion of possible explanations for this dichotomy.
