Rather than creating unproblematic ‘natural' spaces, the definition of boundaries within protected areas formally reifies the modernist duality of nature and culture, leading to practical management conflicts between protected area managers. The current conception of protected area boundaries is the result of the historical construction of nature and space. The argument retraces the changes in the way these boundaries appeared and were subsequently defined in four consecutive ‘World Congress on National Parks'. The corresponding changes in the definition of insider and outsider are discussed, linked to the conception of what is ‘natural' in the landscape. Such conceptions need to be examined critically, particularly if the expressed desire of ranscending the modernist divide is to be realised in the future.