In the broadest sense, Mixed and Augmented Reality experiences mix sensory and conceptual elements both externally in the world and in the minds of their users. The question of how participants in these experiences derive meaning from these hybrid realities is important for both analysis and design. By focusing on MAR cultural heritage walking tours, this paper develops a theory of meaning-making based on the aboriginal walkabout that accounts for both physical and conceptual experience. Through an interweaving of concepts from anthropology, architecture, design, cognitive science and MAR itself, I demonstrate that his theory is compatible with known principles of brain function and human behavior and thus it serves as a more general theory of meaning-making applicable beyond the MAR walking tours from which it was derived.