[nine_k]

Bury it back. We seem to have huge cavities from used-up coal mines. We could refill them.

[luck_fenovo]

I have a new answer for the Fermi paradox. Any sufficiently advanced civilization will develop an extreme "leave no trace" view for ecological reasons.

They refill coal mines, plant trees where there were once cities, and silence radio emissions so that everything appears to be in its "natural" state.

[schiffern]

"Any sufficiently advanced civilization is indistinguishable from nature."

[jacobush]

Love it!