Massa Marittima is a town and comune of the province of Grosseto, southern Tuscany, Italy, 49 km NNW of Grosseto. There are mineral springs, mines of iron, mercury, lignite and copper, with foundries, ironworks and olive-oil mills. At Follonica, on the coast, are the furnaces in which are smelted the iron ore of Elba.
The town appeared in the early Middle Ages, the bishopric seat of Populonia being moved here around 1000 AD. After the initial domination of the Republic of Pisa, it became an independent commune in the 13th century. In the following century it was conquered by Siena, to which it belonged until it became part of the Grand Duchy of Tuscany in the mid-16th century.