Human settlement of the moon For all the discussion of Mars, it is noteworthy that despite its relative proximity, there has as yet been just one brief occasion, 50+ years ago, where humans have landed on the moon (the US Apollo 11 manned moon mission), and nothing since. There is momentum building to go back and stay. The European Space Agency (ESA) has been discussing a moon village concept with a community of private and government space partners. And the Japanese Space Agency (JAXA) has just discovered 50km long x 100m wide lunar caves (lava tubes) created by volcanic activity on the moon 3.5b years ago, which could be a promising beach-head for permanent settlement.

Article: Lunar Caves, The Guardian, 19th Oct, 2018, Justin McCurry:
https://www.theguardian.com/science/2017/oct/19/lunar-cave-discovery-raises-hopes-for-human-colonisation-of-moon

Article: Moon Village, The Guardian, 2nd Dec, 2016:
https://www.theguardian.com/science/2016/dec/02/moon-village-concept-attracting-worldwide-support-european-space-agency-lunar-outpost