What'll really bake your noodle is the fact that we most likely couldn't tell if there was a pre-human civilization on earth, even around industrial levels. What we have now will easily last a thousand years - but not a thousand thousands years.
And my favorite hypothesis: Antarctica. If there ever was a species which flourished there, it's a lot harder for them to colonize the rest of the world than it is for us to visit Antarctica. Clothes you can just wear, and heating is pretty straightforward - but having to venture in a place where portable aircon failure means death will pretty much guarantee you don't build a lot far from home. Which puts a pretty high limit on how far a civilization could have gotten there and still have all traces hidden in the ice.
I doubt this is really true. We've identified many traces of life from millions of years ago. You don't think we could find some bricks or beams from an industrial civilization?
And my favorite hypothesis: Antarctica. If there ever was a species which flourished there, it's a lot harder for them to colonize the rest of the world than it is for us to visit Antarctica. Clothes you can just wear, and heating is pretty straightforward - but having to venture in a place where portable aircon failure means death will pretty much guarantee you don't build a lot far from home. Which puts a pretty high limit on how far a civilization could have gotten there and still have all traces hidden in the ice.