Ecology and cybernetics, in their everyday folk meanings at least, might seem to be completely dissociated fields: the first suggest- ing the study of living organisms in their environments, and the other conjuring images of automation, machines, and their con- trol and management. They share however a concern with under- standing systems, and as even the most cursory study shows, the histories of these concepts are intimately intertwined with each other. In fact, I argue that they have a common structure in a certain abstract spatial imaginary which determines think- ing about systems in modernity. This spatial abstraction itself emerges through a new division of labour which transformed our production and thinking about bodies, machines, and buildings. This is the story of three architectural typologies—the bounded cell, the networked field, and the observatory tower—, a story which raises questions about the nature of architecture and its relationship to other forms of technical and scientific knowledge, and to systems theory in general.