Here’s what you’ll learn when you read this story:Researchers tracked Celtic silver coins to a mountaintop site in Croatia. After years of excavation, archaeologists from the University of Zagreb located a 3,200-year-old fortress with stone defenses. What they found was an astonishing 3,200-year-old stone fortress. Today we hit the jackpot.”The mountaintop excavation first exposed stone ramparts, but further investigation showed that was just the beginning. Potrebica said that the find forces the research community to rethink the previously accepted social and cultural norms of the Balkans during the Bronze Age—all thanks to some black market Celtic coins.