Castle of the Subterranean City

An imposing medieval-style castle carved into a vast underground city, perched atop a basalt outcrop inside a glowing subterranean cavern. The castle is built of weathered stone with ivy clinging to mossy walls, towers and crenellations rising above a network of tunnels and arched bridges spanning subterranean chasms. The scene is painted in oil with rich textures, thick impasto, and dramatic chiaroscuro. Warm ochres, burnt siennas, and umber tones mingle with cool blues and emerald reflections from bioluminescent fungi and molten lava rivers. The air is misty with mineral dust; distant tunnels fade into shadow. The mood is epic and mysterious, like a Renaissance oil painting rediscovered in a cave, with a slightly elevated viewpoint and ornate gate guiding the eye toward distant columns receding into the underground city.