The bluestones in Stonehenge come from West Wales. Instead of quarrying stone from near the monument, they dragged these huge blocks from ~278km away. Likewise, the altar stone comes from ~700km away in North-East Scotland. It must’ve been very important for the ancient Britons to’ve used these specific rocks for some reason, but their religious practices were conveyed via a now extinct oral tradition so no-one knows exactly why they did it.