Underground housing, underground businesses, etc. Would that be better for the environment + possibly save on energy costs? Also possibly safer in certain scenarios like tornadoes etc.
Potential issues that immediately come to mind are ventilation, earthquakes, and flooding. But it’s not like underground dwellings/basements/etc. aren’t a thing, so maybe those issues have been addressed in ways I’m not familiar with.
It’s cold because it has a large thermal mass and nothing heating it up.
Human civilization produces a lot of heat. The thermal mass means it might take years or decades to reach its heat equilibrium. But that equilibrium will be excruciatingly hot.