I have been planning it out but only for my property. I can not afford to build the national, international or interplanetary bits. Getting a good team together at my location is my only obstacle. It's very hard to find a solid general contractor and team here that will build as designed in phases. They want to do it all in one shot but that introduces a lot of legal risk if they are doing it wrong.

I love being underground. It's cool and quiet. Those facilities also last a very long time. I found many "Kilroy was here" scribbles in tunnels in the military and some of them were dated back to WWII.