Building below ground gives some insulation against solar radiation, too. They are unprotected by our magnetic field. They’ll need to do that on Mars, too, I believe, for the same reasons. No magnetic field.
I heard some conversation last night on George Nouri’s show about the Mars thing. Uh, I don’t think I’ll be volunteering to take that one on. I’d miss my dog too much and I don’t even have one anymore.