The Tricastin () is a natural and historic region in the southern Rhône valley of southeastern France comprising the southwestern portion of the Drôme department and the northwestern portion of Vaucluse and centered on the modern town of Saint-Paul-Trois-Châteaux. The region is the cradle of the ancient Tricastini tribe, whose capital was Augusta Tricastinorum under Augustus's reign, now Saint-Paul-Trois-Châteaux. The name Tricastini, which for a long time was interpreted as meaning "the land of the Three Castles" in reality derives its name from the Gallic tribe the 'Tricastini', which occupied the territory during the Roman period. Nowadays, the Tricastin region is known as the site of the Tricastin Nuclear Power Plant situated on the Donzère-Mondragon canal, a tributary of the Rhône, for its Rhône valley AOC wine grape Grignan-Les Adhemar, and for its natural and architectural endowment. History The Tricastini were an ancient Gallic tribe that gave its name to the region. Pliny the Elder spoke of their capital named Augusta Tricastinorum in Natural History, Book 3, corresponding to modern Saint-Paul-Trois-Châteaux. Tricastin was considered as the "land of white stone" due to the fact that it is one of the only areas of the Rhône valley where the stone has such a light color. Numerous quarries were active up to the middle of the 20th century in Saint-Paul-Trois-Châteaux and Saint-Restitut. The capital Saint-Paul-Trois-Châteaux was the seat of a bishopric until the French Revolution when it was dissolved, the same fate as those of Uzès and Vaison-la-Romaine. The southern Tricastin town of Bollène was a commercial center during the whole medieval era and its center still contains traces of its flourishing past. Pont-Saint-Esprit and Bourg-Saint-Andéol, located on the western border, are also very old settlements where the mark left by religious influence is still very evident. They remained pilgrimage sites throughout the medieval era up until the French Revolution, and house numerous religious communities today. In modern times, the 20th century saw vast improvements in the transportation infrastructure. More recently, the Tricastin nuclear power plant has attracted protests by anti-nuclear groups such as Greenpeace. Environment Geography Located in the southern Rhône valley, the Tricastin plain extends from the Donzère canal (bordered by the autoroute of the South) on one side, and by the ancient riverbed of the Rhône on the other. To the north, it extends to the narrows at the Pont du Robinet bridge, and to the south, to the