Centuries prior to World War IV, the moon was colonized by a small group of researchers from many different countries to further space research and exploration. After sixty years, the colony was recognized as its own country: Luna, a republic.
All Lunar cities are housed beneath a series of interconnected paraterraformed domes. The domes are made out of regolith, a substance found in abundance on the moon, that has been fused into a thick glass-like substance. The majority of the city's buildings are made of cast regolith, giving them a matte black finish. Other natural building materials include basalt rock, titanium, and silicon. Beyond the domes, the sky is always black and stars are always visible. Earth can also be seen from those domes on the Earth-facing side of Luna, and it is sixty times brighter and four times larger than the Moon appears from Earth.
One Lunar day and night lasts about twenty-eight Earthen days—what is seen as one moon cycle, from full moon to full moon. Lunars designed the domes to go opaque during the long days or produce artificial sunlight during the long nights in order to simulate Earth's day-and-night patterns. Energy is derived from solar power collection stations around the "peak of eternal light," or the rim of the Peary crater. They are linked on a grid and transferred to the city. Water is available as perpetually frozen ice in nearby continuously-shaded craters.
Luna's capital city, Artemisia, is located on the Earth-facing side of the moon near the North Pole at the edge of Mare Frigoris, or the Cold Sea. It is the hub of government activity and the home of the Lunar royal family and other aristocrats. Other outlying domes serve distinct purposes and were designed with different industries in mind, including regolith mining and processing, goods manufacturing, and agriculture.
Travel between domes takes place entirely beneath the moon's surface in a complex subway system, largely built using existing lava tubes. Atmosphere-controlled lava tubes also serve as ports for incoming and outgoing spaceships.
Videos and messages from the royal family and high courts are broadcast from the walls of the domes and screens along the underground subway systems. These are on a closed circuit and controlled entirely by the government—lower-class Lunars do not have access to news or information from Earth.