The Zollfeld valley has been a cultural and political centre since Celtic tribes settled in the region. When their kingdom of Noricum had become a province of the Roman Empire in 15 BC, Emperor Claudius had the city of Virunum erected as the province's capital at the foot of the nearby Magdalensberg, where on the hill top a splendid Celtic settlement had already existed. Virunum became a centre of early Christianity in the early 4th century as the see of a bishop under the jurisdiction of the Patriarch of Aquileia.