It was the aliens

 Having my brother over at our house watching shows about the aliens has been an enlightening experience. I'm so enlightened now. Let me sum up the experience: 

NARRATOR: Our voyage through the ancient civilisations takes us to the pyramids. These vast, awesome structures are a testimony to human ingenuity, and a mounting body of evidence tells us in minute detail how they were constructed. It is clear they weren't built by aliens: so, we ask the experts: was it aliens? 

PYRAMID EXPERT: No. 

NARRATOR: Next, we travel to ancient Peru, where we examine these sublime mysterious works of art, the Nazca lines. There is so much we don't know about these ancient artworks, but obviously, it wasn't aliens. Or was it? 

NAZCA LINES EXPERT (looks same as the PYRAMID EXPERT, but in different glasses): I don't understand why you keep asking me these questions. 

NARRATOR: So it was, was it. 

NAZCA LINES EXPERT: Oh, FFS... 

NARRATOR: That's all right. Your silence says more than words ever could. 

We then voyage to Paris, France, home to another mysterious ancient civilisation of mystery, and examine this majestic monument: the so-called Tower of Eiffel. Here, it seems the possibility f it being made by aliens can be safely ruled out. Or can it? 

PARIS EXPERT: Yes. 

NARRATOR: So you're saying it was aliens after all? 

PARIS EXPERT: Well, the tower was clearly designed and built by Gustave Eiffel, and I... 

NARRATOR: Never heard of him. 

PARIS EXPERT: .... if I could just... 

NARRATOR: Really makes you wonder, doesn't it? 

PARIS EXPERT: ... and here are the historical documents, showing... 

NARRATOR: It is yet another mystery hidden in the ancient past. 

PARIS EXPERT: Why are you even bothering to ask me, if you just... 

NARRATOR: La la la la la. I guess we'll never know. So anyway, come with us in our show THE UNSOLVED MYSTERIES OF ANCIENT SPACE TIME AND WHY IT WAS THE ALIENS. 

It's great stuff!