[bumbada]

Tunnels are one of the most important things you could build on any planet or satellite like the moon.

Remember there is no atmosphere nor magnetic fields on other planets to protect you from cosmic rays, so a good solution is make people live underground.

Some time ago a teacher offered me to make my Master thesis on that(I did not take it) because there were people already working on this problem.

BTW, places like the moon are very interesting. Because there is no fluid erosion every single grain of sand is extremely abrasive.