alt Hacker News> that it might only take a couple of million years, to completely wipe all traces of even an advanced, mechanized civilization.
It depends who comes searching. u235 has a half-life of ~700m years, so finding it in enough places (i.e. rocket silos, even if underground) and obviously processed into spheres, would raise some advanced alien eyebrows. There's also a chance that some things we left on the Moon / in high orbits will survive for a few million years. (also the test tubes on Mars and the rovers themselves, some have RTGs which, even if "depleted" of usable energy might still register as artificial)
Items degrade but what often remains is imprint of it in surrounding material, that over time becomes rock. We dumped enough shit all around us that is too smooth/right angled/whatever to look like natural product. If anybody digs enough, they will find enough evidence, direct or indirect.
That is, till all currently-up tectonic plates submerge for melting. But since they don't move by same speed, some of it will probably remain around till sun inflates and scorches surface or even absorbs Earth. That will be probably it, melted surface will hide or destroy all of it. But thats what, 1 billion years in future?