“There have also been alien implants as well as ground traces of craft if that is your thing.”
that’s the best you can do? After more than 75 years? Pathetic.
I have 100,000 years to work with—and yeah it is the best I can do other than a few cave paintings here and there.
They have been here a lot longer than we have—and left no “evidence” that meets your exacting requirements.