The area that was known as Gaul in Roman times includes modern France, and also Belgium, Luxembourg and western parts of Germany.
The conquest of the region by the Romans began in the 2nd - 1st centuries BC, and continued with the 'Gallic Wars', led by Julius Caesar, between 58 BC and 51 BC. At that time the region was also under threat from other directions - notably the Suevi and Helvetii tribes (from modern day Germany and Switzerland) - and initially it was defeating these tribes that posed the greatest challenge to the Romans.
It was in 53BC in Alesia that the final great battle took place between the Gauls and the Romans. The gauls, fighting under , were defeated by Julius caesar and the Romans, and the Romans can be considered to have occupied France from that date on. The exact location of Alesia is still debated, although the most likely location is in Burgundy at Alise-Sainte-Reine near Dijon.
From about 53 BC onwards the focus of the Romans in the Gallic Wars was more on suppressing a series of smaller invasions and uprisings - including 52 BC when a group of tribes led by Vercingetorix posed a significant threat to the Romans, but this threat was also defeated. (Enthusiasts of Asterix and Obelisk, the extremy popular French cartoon characters, will be familiar with this period!)
Rome then controlled the area for about six centuries, until the Roman empire itself collapsed, in the face of constant invasions.
Romans in France built a number of fine villas and, notably, introduced vines from Italy. The heyday of the Romans in Gaul was during the first and second centuries AD, when there was little unrest and the later tribal invasions from the north and east had not yet started - it was a prosperous area, with prosperity built largely on potterey, wine and food exports.
Until the Roman occupation, the predominant religion was druid based and very primitive. It was while under Roman rule that Christianity was introduced, and that Claudius I ordered the Druids suppressed. At the same time, the Gaulish language spoken underwent a fundamental transformation, and by the end of Roman rule the language spoken was a Latin based precursor of modern day French.
By the time the Romans left, to defend their homeland in the face of repeated invasions from the Visigoths, the Huns, the Vandals and others, (later as we know to prove successful), towards the end of the 5th century, the basic shape of Modern France had started to emerge.
Although the Franks successfully invaded Gaul, they did little to alter the society that was by that time established. Gaul was soon established, with a King based in Paris, and the 'modern history of France' began.
Visiting Roman monuments in France
There are many locations in France where you can see ruins dating from the period of Roman occupation.
The greatest concentration of these, and the best place to start your exploration of Roman France, is in the south of the country near the border between Languedoc and Provence - highlights include the Pont du Gard aquaduct, the amphitheatre at Orange, and the colosseums at both Nimes and Arles, all found in quite close proximity to each other.