The first settlements date from 1500 BC. The Brigantii are mentioned by Strabo as a Celtic sub-tribe in this region of the Alps. In the 5th century BC, the Celts settled at Brigantion, which became one of their most heavily fortified locations. After a series of battles in 15 BC, the Romans conquered Brigantion and the city became a Roman camp. It was conferred the status of a municipality (Brigantium) around 50 AD and was the seat of the Roman admiralty for Lake Constance. In 259/60 Brigantium was destroyed by the Alemanni, Germanic peoples who settled in the area in around 450.