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.
Putting big roads underground is what norway does, once you see it done it becomes very obvious that it should be standard (plus it helps prevent large roads from being built at all, which is even better).