Get the Popular Science daily newsletter💡 Breakthroughs, discoveries, and DIY tips sent six days a week. An amateur archaeologist armed only with satellite imagery and a hunch helped uncover evidence that’s reshaping how historians understand the Roman Empire’s advance into present-day Germany in the third century CE.  In 2020, hobbyist Michael Barkowski was combing through aerial imagery available online, when he spotted an unusual formation near the town of Aken, in the state of Saxony-Anhalt in northwestern Germany. Barkowski suspected that the large rectangular outlines and apparent ditches he was seeing could be signs of marching camps that were commonly deployed by Roman legions. Although remains of such camps have been identified elsewhere in Germany, historians had not found evidence of any this far north. After Barkowski reported the sightings, professional archaeologists from Germany’s State Office for Heritage Management and Archaeology Saxony-Anhalt conducted their own aerial surveys. Their findings confirmed Barkowski’s hunch—and then some. Subsequent surveys revealed not just one, but four Roman marching camps spread across towns in the state dating back to the …