A disk-shaped, spiral-shaped, futuristic building built on the surface of the moon. Supported by several steel pillars, the building seems to float in midair. The building is shaped like a snail's shell, so it can be permanently extended. It is already about 1 km in diameter. There is no air outside, so people can only live in buildings. Thousands of stars in the sky. The blue earth is also visible. In the distance, lunar craters can be seen, but no large mountains are visible. Above the building, there is an airship docked.