Caesarodunum. (Altionos, Civitas Turonum, Turoni) modern Tours, Indre-et-Loire. A town in west-central Gaul, beside a crossing of the river Liger (Loire), just above its confluence with the Caris (Cher), at an important meeting of roads running down their valleys and converging on the main route to the Atlantic. Capital of the small tribe of the Turones, the place played an important part in native resistance during the Gallic Wars of Julius Caesar (whose name it subsequently incorporated) in its new designation Caesardunum. After the creation of the Roman province of Gallia Lugdunensis, it again fulfilled a prominent role in the Gallic revolt under Tiberius (21 AD).

Destroyed by a German attack in 275, the town was equipped with fortifications; and- in the later empire- reverting to the name of Civitas Turonum or Turoni, it became the capital of the province of Lugdunensis Tertia. Its greatest distinction in ancient times, however, was owed to the episcopate of the Pannonian St. Martin of Tours (372-97), who also founded a monastic community, Majus Monasterium (Marmoutier), outside the city. During the centuries that followed, St. Martin's fame as a dominant ecclesiastical figure and missionary and miracleworker brought thousands of famous pilgrims to his shrine. In the late 430s or 440s, the city was threatened by an invasion of rebellious Aremorici (from Britanny), and after various subsequent vicissitudes came under the control of the Franks under Clovis, whose investiture as a Roman consul took place in the town (508). St. Gregory of Tours, the great historian of the Franks, was the bishop of Turoni and died there in 594.

The Romans moved the city from the right to the left bank of the Liger. Its principal well-preserved monument is an amphitheater dating back to the second century AD, which is one of the largest in the empire. Portions of the massive third century wall have also survived, and recent discoveries include a fourth century building complex and rampart beneath the medieval castle.