The ultimate ski tunnel, your wishes please?

Alright, so we all pick natural snow in the outdoors over man-made indoors. But mother nature and father greenhouse may not give us many of the latter in the 21st century. And, indoors would open up the summer season for on-snow exercizing.

Countless ways to go about building a ski tunnel, let's explore some, and things we feel strongly about, should someone build one around the corner?

I heard of an initiative that could turn an abandoned road tunnel thhrough a mountain into a ski tunnel. Ideal, I would say, as the air temperature inside wouldn't be too much over freezing to start with, with the mountain making for good insulation? This one won't happen in my country though (no mountain tunnels). I could imagine an under ground structure though, dig a hole, build a roof, throw dirt on and let stuff grow.
But if you suppose a big hall, how to best use the room at hand? Many overlapping stretches, to get the most snow surface per outer building surface, and most efficient insulation? Also a longer, less boring track, of course.

I though maybe to gather even thin ice from outside, and direct it to below the hall, to get "free cold" to store for the off-season. Should be more eco-friendly, and especially energy-bill-friendly. A roof with solar collectors and wind mills might further help get the ski tunnel a bit towards being self-energy-supporting.

Stage televised races on a spectacular course to attract sponsors?

Any positive ideas posted here might help free financial backing around the world for ski tunnels.

Happy trails,

J