Cinematic film still of a spiral Art Nouveau staircase inside an abandoned 1920s sanatorium, shot from low angle looking upward through the spiral core, wrought-iron balustrade with peeling cream enamel paint revealing rust scars and oxidation patches, Carrara marble steps cracked with hairline fissures filled with moss cushions and lichen growth, worn edges on treads from decades of footfall, cold moonlight streaming through frosted skylight dome casting hard geometric shadows across the stair treads, dust particles suspended in the light beams, damp concrete walls with water stains and peeling plaster, single dead fern in corner, anamorphic lens flare from moon, shallow depth of field isolating mid-section of spiral, rich desaturated color grading with teal shadows and amber highlights, shot on ARRI Alexa 65 with Panavision anamorphic lens 2.39:1 aspect, cinematic grain structure, liminal space aesthetic, dark academia mood, 8K resolution, no watermark, no text artifacts, no people, no oversaturation, no artificial glow