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.
Don’t forget fires as a hazard. When you’re underground, there are fewer windows to jump out of
Or mold/air quality. When you’re underground there are fewer windows to open
Plus more people would be S.A.D. There you’re underground there are fewer windows to let sun in