Aosta (äôˈstä) [key], city (1990 pop. 36,339), capital of Valle d'Aosta region and of Aosta prov., NW Italy, near the junction of the Great and Little St. Bernard roads. Aosta is an industrial and tourist center. It has used its position at the confluence of the Buthier and Dora Baltea rivers to produce hydroelectric power. Manufactures include iron and steel, aluminum, and chemicals. Emperor Augustus there founded (c.25 B.C.) a colony called Augusta Praetoria, on the site of an older settlement. In the 11th cent. Aosta was given as a fief to Count Humbert I, the founder of the Savoy dynasty; the cadet line of the house bore the title of duke of Aosta. Roman remains in Aosta include walls and gates, a majestic triumphal arch honoring Augustus, a theater, and an amphitheater. There is also a fine cathedral (12th–19th cent.).