The interior of a cathedral built from an infinite Menger sponge. A box has its central cross carved out three times over and is then tiled forever, so the fractal holes line up into axial tunnels — naves, aisles and pierced stone screens that repeat to the vanishing point. The camera weaves slowly down the central nave while warm sunlight floods through the openwork and hangs in the air as volumetric god-ray haze, brightest toward the sun and sliced by the passing mullions. Cold grey stone against warm light; hover to look around, scroll to advance down the nave, press to make the sun blaze.