Someone left these marks in the sand. We had to find out who. Subscribe and turn on notifications 🔔 so you don't miss any videos: goo.gl/0bsAjO Deep in the Sahara, far from any towns, roads, or other signs of life, is a row of markings in the sand. There are dozens of them stretching for miles in a straight line in central Algeria, each consisting of a central point surrounded by a circle of 12 nodes, like numbers on a clock. And when we started making this video, no one seemed to know what they were. We first saw the circles back in September 2021, after finding a Reddit post on r/WhatIsThis with coordinates asking what the circles could be. With just two upvotes and two commenters, it wasn’t exactly a lively discussion. But seeing the circles themselves on Google Earth was fascinating: They were eerily perfect in their shape and regularity, but so deeply isolated in the desert. We were hooked on finding an answer. So we decided to make a video out of trying to solve th...