A colossal underground waterfall metropolis built into a massive vertical chasm reaching into the Earth's core, towering luminescent crystal platforms cascading down translucent rock faces with bioluminescent architecture, roaring waterfall gardens flowing between glowing obsidian towers, magnetic levitation trains racing through mist-filled canyons far below, deep sapphire and molten gold palette with shafts of golden light piercing from chasm opening far above, epic downward shot with tiny silhouetted workers on illuminated maintenance platforms emphasizes impossible vertical scale, photorealistic, cinematic depth of field