There’s a similar facility called Iron Mountain in Boyers, PA that stores, among other things, millions of government records:

https://www.pennlive.com/news/2021/01/inside-iron-mountain.h...

This is normal storage space, anyone can rent it out.

tl;dr: There's an old limestone mine that rents out space. Ford is a major customer, they store old cars there.

Pretty cool but doesn't need the mystery. I wouldn't mind visiting, although I'm not a big fan of Ford. Seeing an old Ford GT might be cool.