RIOM, a town of France, capital of an arrondissement in the department of Puy-de-Dôme, in a rich and beautiful country, on a hill above the Ambone, 8 miles N.N.E. of Clermont. It is encircled by boulevards shaded by trees, and has a cheerful aspect, though built of dark lava from the neighbouring quarries of Volvic. The streets are broad, and the houses generally are well built. Many of the public buildings, such as the court-house, prefect's residence, hospitals, &c., are very handsome; and the church of St Amable is a curious and interesting old edifice. On one of the boulevards of the town is a granite monument to General Dessaix, who fell at the victory of Marengo. Riom is the seat of several law courts and of a college. It has manufactures of linen fabrics, leather, brandy, and other articles; and a considerable trade in these, as well as in corn, wine, fruit, oil, &c. It was formerly the capital of Auvergne, and the old ducal palace is now the court-house. Pop. (1856) 10,078.