We have extensive cave paintings on our ranch, located somewhere in the USA. Private land.
Go in for a solid mile. Some are exquisite.
Obvious man-made structures, once you get past the bend, even a ventilation tunnel. Lots of trash pits near the cave entrance, filled with bones of various kinds, literally tons of flint work, and what we think are probably burial remains. We just left all alone, excepting to board over the cave entrances.
My grandfather looked at me, dead serious, when I was 12, and told me to tell NO ONE. Not even a friend.
He said it, to let it be known was the quickest way for us to get our ranch confiscated by the federal government.
We finally let our kids see them when they were adults.
Your grandfather was a wise man.
Like finding a treasure trove- shovel and shut up.