Lets take this tunnel down in to the depths of the planetary crust. in Future Mars.
But I’m going to add some bits to this site…
Watch that water table, that lamp looks expensive.
Down here, are large caves. Lots of mechanical things, and electrical wires. Robots, some obvious, walk with humans… with pointy ears and small lobe ears. Elves ? Well, I dont think so.
There is an Annual issue sold by Profantasy that helps map side-views of underground areas. I’ll look into that.
That is it for the time being.
Here is an example: