The Sphinx is the alpha dog — or rather alpha lion-eagle-woman-thing — of unsolved historical mysteries. In mythology, the sphinx was hands-down the best riddler ever, so it's fitting that the most famous representation of it, the Great Sphinx of Giza, is itself an enigma. There has been huge controversy over when this monument was built, who built it, and what it even is. It's a pretty interesting debate, with input from Egyptologists, geologists, archeaologists, and other -ologists who have devoted their life to better understanding the perplexing statue, which is by far the largest that has survived from the ancient world.
It makes you wonder what unsolved mysteries we're currently leaving for future civilizations. Will our descendants shake their head and wonder why this strange "YOLO" word is graffitied onto so many buildings? Only time will tell.