Underground Treehouse Over a Cavern City

Photorealistic 3D render of a treehouse tucked inside an underground city carved into a vast cavern. A sturdy, weathered timber treehouse with mossy shingles sits above polished concrete and steel tunnels. Giant roots wrap around stone pillars, supporting cables and a glass skylight that reveals a dark mineral ceiling. Warm amber lanterns cast soft pools of light on carved wooden floors, rope ladders, and a balcony with a wooden railing. The subterranean city below features curved tunnels, bioluminescent fungi lighting, neon signage, steam vents, and reflective pools. High-detail textures, subsurface scattering on wood and leaves, volumetric fog, and cinematic depth of field; lighting blends daylight through the skylight with artificial glow from the city, creating a scale-rich, earthy futuristic aesthetic.