A colossal volcanic megacity constructed within a massive caldera lake of molten lava spanning kilometers, towering obsidian skyscrapers with integrated heat-exchange membranes glowing soft molten orange, suspended lava-shelf districts with floating ember-garden terraces between massive basalt formation arches, sleek magma-cruisers gliding through intense thermal light between luminous fire fountains, tiny vulcanologists dwarfed by mountain-sized cathedral-volcanoes navigating between illuminated extraction levels, deep obsidian black and electric magma palette with soft eruption glow filtering through infinite smoke layers, epic upward composition from caldera floor traveling upward through massive elevator tubes emphasizes impossible geothermal engineering scale, photorealistic, cinematic depth of field