Unknown to Julius Caesar, Rouen was founded by the Gaulish tribe of the Veliocasses, who controlled a large area in the lower Seine valley, which retains a trace of their name as the Vexin. They called it Ratumacos; the Romans called it Rotomagus. Roman Rotomagus was the second city of Gallia Lugdunensis after Lugdunum (Lyon) itself. Under the reorganization of the empire by Diocletian, Rouen became the chief city of the divided province of Gallia Lugdunensis II and reached the apogee of its Roman development, with an amphitheatre and thermae of which the foundations remain. In the 5th century, it became the seat of a bishopric (though the names of early bishops are purely legendary) and later a capital of Merovingian Neustria.
The Middle Ages
From their first incursion into the lower valley of the Seine in 841, the Vikings overran Rouen until some of them finally settled and founded a colony led by Rollo (Hrolfr), who was nominated count of Rouen by the king of the Franks in 911. In the 10th century Rouen became the capital of the Duchy of Normandy and residence of the dukes, until William the Conqueror established his castle at Caen.
In 1150, Rouen received its founding charter, which permitted self-government. During the 12th century, Rouen was probably the site of ayeshiva. At that time, about 6,000 Jews lived in the town, comprising about 20% of the population. In addition, there were a large number of Jews scattered about another 100 communities in Normandy. The well-preserved remains of the yeshiva were discovered in the 1970s under the Rouen Law Courts and the community has begun a project to restore them.
In 1200, a fire destroyed part of the old Romanesque cathedral, leaving St Romain's tower, the side porches of the front, and part of the nave. New work on the present Gothic cathedral of Rouen was begun, in the nave, transept, choir, and the lowest section of the lantern tower. On 24 June 1204,Philip II Augustus of
