Auxerre was a flourishing Gallo-Roman centre across one of the main roads of the area, the Via Agrippa (1st century AD) and on the Yonne River. In the 3rd century it became the seat of a bishop and a provincial capital of the Roman Empire. In the 5th century it received a Cathedral. In the late 11th-early 12th century the existing communities were included inside a new line of walls built by the feudal Counts of Auxerre.