FOSSOMBRONE, a town of Italy, in the province of Pesaro and Urbino, about 7 miles from Urbino, on the left bank of the Metauro, which is there crossed by a fine bridge of a single arch. It is commanded by an old castle on the heights, and it possesses a cathedral with ancient inscriptions and pictures, a Capuchin church, a seminary, and the vestiges of a Roman theatre. There are several silk factories in the town, and the silk produced in the district ranks as the finest in all Italy. The population of the town proper in 1371 was 3821, and of the commune 9056.

Of the origin of Fossoιnbrone nothing is definitely known. It appears by the name of Forum Sempronii as a flourishing municipal town under the Roman empire. Ruined by the Goths and Lombards, it was soon afterwards restored on a slightly different site. The Malatesta and Galeazzo families had for a long time possession of the lordship, but they sold it in 1440 to the duke of Urbino.