All BS aside, Stonehenge mysteries really tickle the mind. Those were very stubborn and determined people to put in such a gargantuan effort to transport those stones and then build it. It is unsettling that it was considered an ancient mystery even to the Druids. We don’t know who we are.
Some of the best-known great monuments appear to mark a cultural/political peak that's about to followed by s steep decline. F'instance, the Giza / Abu Roash pyramids (Khufu, Djedjefre, Khafre, Menkaure) are considered 4th dynasty, but Menkaure's son and successor is the considered the first of the 5th dynasty, which regressed to mastabas instead of a pyramids for pharaohs' burial monuments.
Whoops, my mistake, when the 5th d burials moved to Saqqara, they still used pyramids, but they were pretty crappy ones.