This paper develops a representation-theoretic notion of spatial context for cognitive agents interacting with spatial environments. We discuss the current state of the art in defining context as used in context-aware and/or location- aware systems. In contrast to existing approaches, we define context through cognitive processes. The term "invisible geography" alludes to the fact that knowledge about geographic space develops through complex cognitive interaction and is not simply "out there" to be looked at. Placing (cognitive) processes in the focus of our context definition allows for a truly user-centered perspective: conceptualizations imbue spatial structures with meaning. This allows for fixing terminological problems and relating context definitions to work in spatial information theory and cognitive science. Although we focus on spatial context, the approach is generic and can be adapted to other domains in which cognitive aspects concerning users of information systems are central.