Lava tubes seem like they would be ideal, if we can find them in places that would be good for settlement. https://en.wikipedia.org/wiki/Martian_lava_tube http

Lava tubes seem like they would be ideal, if we can find them in places that would be good for settlement. https://en.wikipedia.org/wiki/Martian_lava_tube https://en.wikipedia.org/wiki/Martian_lava_tube