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 the mystery, no matter where it took us. We documented every step of the process — from Zoom calls and web browser screen recordings to vlogs and field shoots — to show the reporting process from the inside out. And when we maxed out what we could learn on the internet, we handed over this story to a team in Algeria to take it all the way.