The principal Roman city of northeast Gaul and important medieval administrative and trade centre situated in the Moselle Valley. The site was settled in the later 1st millennium bc by the local Treveri tribe who appear to have built a tribal sanctuary there. Following the Roman conquest of Gaul the site was selected by the emperor Augustus as the regional capital because of its favourable position in relation to the Rhine frontier as a supply base to the Roman army, for regional trade, and as an administrative centre for the three provinces of Gallia Belgica and two Germanies. By the 4th century ad Trier had become a spiritual and political capital for western Europe and later was the centre of an archbishopric.
E. M. Wrightman, 1970, Roman Trier and the Treveri. London: Hart‐Davies