FOSSOMBRONE, a town and episcopal see of the Marches, Italy (anc. Forum Sempronii), province of Pesaro and Urbino, II m. E.S.E. of the latter by road, 394 ft. above sea-level. Pop. (1931) town, 7,239, commune, 10,408. The town is in the valley of the Metauro, at the meeting-point of roads to Fano, to the Furlo pass and Fossato di Vico (the ancient Via Flaminia), to Urbino and to Sinigaglia, the last crossing the river by a fine bridge. Above the town is a mediaeval castle. Silk throwing is carried on.
The ancient Forum Sempronii lay about 2 M. to the N.E. at S. Martino al Piano, where remains have been found. It was a station on the Via Flaminia. Excavations have led to the discovery of houses and of other buildings on the ancient road. It already had a bishop in the years