We call them the Celts – bloodthirsty warriors who fought naked in battle and took their enemies heads as trophies. They had powerful priests called Druids, who practiced human sacrifice to their gods, and a distinctive artistic style now sold as jewellery across the world. Evidence of Celtic civilizations stretch across Europe, in Germany a huge walled settlement is unearthed, in Switzerland thousands of artifacts illustrate the distinctive Celtic artistic decoration. Excavations in northern Europe uncover a huge engineering achievement. The expanding Roman Empire crushed the Celts in continental Europe and evidence uncovered in Britain and Ireland suggests that migration of a warrior tribe of Celtic settlers occurred, bringing their foreign traditions with them.