Abstract. This paper describes Scene Based Reasoning (SBR), a cognitive architecture based on the notions of "scene" and "plan". Scenes represent realworld 3D scenes as well as planner states. Introspection maps internal SBR data-structures into 2D "scene diagrams" for self-modeling and meta-reasoning. On the lowest level, scenes are represented as 3D scene graphs (as in computer gaming), while higher levels use Description Logic to model the relationships between scene objects. A plethora of subsystems implement perception, action, learning and control operations on the level of "plans", with scenes acting as planner states.