At its most basic level, the built environment refers to all elements of the human-made physical environment, i.e., it is defined in contrast to the natural environment. Dunlap and Catton's (1983) distinction between the “built,” the “modified,” and the “natural” environments is heuristically useful inasmuch as it more readily acknowledges the intermediate, mediative, and continuous possibilities of interaction and reciprocal relations between and among these divisions. Given its essentially contrast-dependent definition, it is not surprising that the term has become increasingly in vogue in the era of environmental consciousness.