Yeah, I've read about and seen documentaries presenting evidence for those ideas. I mean, considering that we don't truly know the human origins, I wouldn't rule out an alien or otherworldly explanation - at this stage.
@YukikoAmagi I was thinking the same as @Longpatrol,, I've still never seen anything definitive as to Stonehenge's origin or purpose--other than the last Transformers movie, LMAO