ACAD, Alien City Above The Desert, vast extraterrestrial canyon basin under a star-filled night sky, towering alien megastructures and monolithic spires rising along the rim, dark metallic ancient-futuristic architecture, massive hovering spherical machines with glowing blue circular cores and segmented light patterns, floating blue particles like energy fireflies, cold cyan bioluminescent lighting illuminating fog and dust, barren alien desert basin floor of compacted ash-gray soil and gravel, steep quarry-like canyon walls. Several rock formations are in the valley.