A colossal cavern megacity built into a massive underground lava tube network deep within a planet's crust, towering luminescent crystal spires forming organic skyscraper districts illuminated by geothermal glow, suspended glass biodome neighborhoods floating above underground hot springs, magnetic levitation trains racing through crystalline tunnels, massive translucent ceiling domes revealing the planet's surface far above, deep obsidian and molten amber palette with warm geothermal light pulsing through crystal formations, epic horizontal wide shot with tiny silhouetted miners on observation platforms emphasizes impossible subterranean engineering scale, photorealistic, cinematic depth of field