I would have expected a hole drilled into a cave or something like that. A piece of steel attached to a deck probably won't survive 100 years, simply because s

I would have expected a hole drilled into a cave or something like that. A piece of steel attached to a deck probably won't survive 100 years, simply because someone will want to make the deck bigger or better in the intervening time and then the camera will move. That said, that whole pitch drop experiment is going pretty well. It's not quite at 100 years, but it's getting very close. (2027). So that's 1/10th of a millenium. (I will note that the pitch drop experiment has been moved before. It's not nearly as sensitive to movement as a camera.)