Heuneburg

Located in modern day Hundersingen, Germany. Known as one of the earliest urban centers north of the Alps, it was a fortified hilltop settlement and a key center of the Hallstatt culture where salt was mined. Archaeological evidence shows that Heuneburg had advanced fortifications, including mudbrick walls in a Mediterranean style, and a thriving trade network connecting it with the Mediterranean world, particularly with Greek colonies as Greek pottery were found in this site. Around 500 BC, Heuneburg faced a decline, likely due to internal conflicts or pressure from neighboring tribes. While it lost its dominant position, Heuneburg remains one of the most significant archaeological sites of early Celtic civilization, providing key insights into Celtic society, trade, and interactions with the wider ancient world. https://en.wikipedia.org/wiki/Heuneburg