You have not looked then. The evidence is unshakable for at least a very advanced society having lived before the age of current human history. Whether you want to call them "aliens" would depend on where you think they came from, how they knew about the solar system, the planets, and how they flew through the air and built airports, what the ancient computer-like machine was with all gears they found under the sea that was dated older than b.c.

How the pyramids were built, and how some ancient stones were cut and carved with machine-like precision that we don't even have the capability to do today. Some of the lame explanations for how these structures were built are laughable and idiotic. Most of it is simply ignored.

The evidence is there and it is unshakable. You must be blind or just refuse to see it. You prefer to believe the lame explanations. What I wonder is why.