I rather console myself that there are likely many things, built of stone, long lasting things, some of them very massive structures , some very difficult to erect, dotted all over this ancient globe, which were painstakingly built with tons of men and many many more tons of stone, built by people like me and you, who really had no idea what they were doing, not because they were unskilled, but because they had absolutely no concept of why they were doing it.
I imagine Stonehenge to be in this category. The people who came together to build this mysterious configuration of huge standing stones, likely stood back themselves when they were done and wondered what it was actually for, and pondered to understand why exactly they had built it. Thankfully they built it with a material durable enough to last ages and ages, so that it would allow enough time for someone in some future more ‘advanced’ culture to unlock the essential cause for its having been made.
Likely any of the builders back then , who were asked the question "Why was it built?", would have had to answer, ‘because’. And so we join with our stone brothers and sisters of the past, and say “ until the mystery of why we did it, is revealed to any of us, we can only scratch our heads and answer, "Well..mostly, just because !"
( More of the story of how, where, when, what, and who to follow )