Abstract: We describe a conceptual infrastructure - the Luminous Room - for providing graphical display and interaction at each of an interior architectural space's various surfaces, arguing that pervasive environmental output and input is one natural heir to today's rather more limited notion of spatially-confined, output-only display (the CRT). We discuss the requirements of such real-world graphics, including computational & networking demands; schemes for spatially omnipresent capture and display; and issues of design and interaction that emerge under these new circumstances. These discussions are both illustrated and motivated by five particular applications that have been built for a real, experimental Luminous Room space, and by details of the current technical approach to its construction (involving a two-way optical transducer called an I/O Bulb that projects and captures pixels).