Moonbase
A lunar base, moon base, or lunar colony is a theoretical research station, resort or similar establishment on the Moon. As the Moon is only 360,000 kilometers or 250,000 statute miles away from the Earth, it would make an ideal test bed for settlements on other planets and natural satellites. Arguably the best moon colony option would be to place it within one of the Moon's lava tubes, where it would be protected from radiation, micrometeorites, and the wild temperature swings due to the lack of any substantial atmosphere and the lunar day being 672 hours long.