Came across this online issue of the Journal of Cosmology recently. This issue is all about archaeoastronomy, a fascinating field.
Now the obvious rant: “All these archaeo-astronomical structures all over the world — this *proves* the aliens landed and gave humankind advanced knowledge of the stars!!”
My equally obvious response: No, it proves that when you’re on the earth, the sky is seen all over the globe — and people observed it and tried to track and “map” its behavior. If you were patient enough, you could do this in your backyard (I don’t recommend marking with megaliths, though — maybe just drawing lines on your picket fence).