GROSSETO, a town and episcopal see of Tuscany, capital of the province of Grosseto, 90 m. S.S.E. of Pisa by rail. Pop. (1931) 13,719 (town), 23,997 (commune). It is 38 ft. above sea-level. Fortifications constructed by Francis I. (1574-87) and Ferdinand I. (1587-1609) form a hexagonal enciente with projecting bas tions, with two gates only. The small cathedral begun in 1190 and rebuilt in 1294, is of red and white marble, in the Italian Gothic style. The citadel was built in 1311 by the Sienese. Grosseto is on the main line from Pisa to Rome.
The town dates from the middle ages. In 1138 the episcopal see was transferred thither from Rusellae. In 1224, with the rest of the Maremma, of which it is the capital, it came under the dominion of Siena. By the peace of 1559, however, it passed to Cosimo I. of Tuscany. In 1745 the malaria had grown to such an extent, owing to the neglect of the drainage works, that Gros seto had only 648 inhabitants, though in 1224 it had 3,00o men who bore arms. Leopold I. renewed drainage operations, and by 1836 the population had risen to