Why is it insane?

I don't know for what purpose they'd build something like that, but I reckon that's the kind of stuff about anything which is most easily lost. Stuff from millenia ago can easily look like "cow tools". They were mostly agricultural civilizations though, and attached importance to astronomy to some degree because it allowed them to make calendars and plan ahead of time.

I don't think it's nothing out of ordinary that they've built stuff to align with the sky.