I'm reminded of a quote from an old Tom Scott video. He's visiting a modern reconstruction of a Neolithic long barrow. Tom points out that the sun lines up with the entrance on the summer solstice, then it cuts to the owner who says

I think a lot of people would assume that getting the alignments of a monument like this... would involve complex calculations, a sharp pencil, and computing power. But in fact, you can do it just as easily by getting up at the right time with some sticks.