This is such an absurd take. There's people in Europe who believe that Europe's megalithic structures were built during the time of Atlantis and devote their whole existence to proving it, just to give one example. And of course, Stonehenge, neolithic Europes intergalactic landing site/astronomical calendar/astral energy power plant.

Megalithic structures like the Baalbek stones or Göbekli Tepe from preliterate times are aweinspiring enough to get anyone's imagination going, it's that simple. And some people then have a hard time distinguishing their imaginings from reality. They seem impossibly large and their purpose and methods of construction are lost to time, so it's easy to come up with fanciful ideas to fill in the blanks. Sure, we now have decent theories of how the pyramids were built, but that weren't always the case.

Castles and cathedrals were built too recently for even the wildest of wild brains to believe they weren't built by humans.

It also implies aliens are dumb as dirt.

"Hey Xorglib, what did you do on your vacation to Earth? Did you teach them how to cure diseases? Or maybe advance their technology by a millennium or two?"

"Oh. Ummm...I helped them move some stones into a giant 3D triangle to immortalize their god emperor. And that was it."

"Asshole."

We do see Stonehenge included in ancient alien theories sometimes though.

People say the exact same things about Stonehenge.

Utter nonsense. The reason alien conspiracy theories don't exist about castles and cathedrals is because the construction of these buildings was almost always very well documented and in many cases these documents still exist today. As far as I know there are no testimonies on the construction of the Egyptian and Mayan pyramids other than the structures themselves.

Remember one about the inca or something, and they said that there was no way they could cut perfectly fitting stone bricks for their walls, so it must have been aliens or something

Except maybe they just ground out the imperfections after excavating the stone, the exactly the way European masons did.

They stacked things on top of other things? Must be aliens!

You're talking about the same type of people that think the earth is flat. These people don't think about race, they see a mystery and try to see their agenda in it.

Funnily enough (to me), the (white) Anglo-Saxons spoke of the Roman ruins in Britain as having been built by giants, because they could not imagine how they had been constructed.

My social studies teacher was fond of pointing out that people in ancient times had the same size brain we have now and where they lacked academics for math literacy they spent all their time working out tradecraft.

Yes let's make it a race thing. Have you considered that maybe the majority of ancient structures are found in those countries. These countries were more civilized and were building much more sophisticated stuff before white people were. The few ancient white structures that we don't understand how they built and still stand do have conspiracies around them e.g. stonehenge.