The town of Montieri dates to the Etruscan times and it was already famous at the time for the extraction of Copper; in effect, the name "Montieri" means "Mountain of Copper". In this town in the territory of Grosseto with 1000 inhabitants the castle of Montieri and the churches of San Francesco and San Giacomo can be visited.

There are numerous evidences that the territory was an important centre of extraction in the Etruscan times. In effect, many "loppe fusorie" have been found near this chief town ad they were very similar to those found in the more famous area of Populonia, the town that certainly dominated the area of Montieri. In the surroundings, it is also possible to visit the tunnel of the "Buca delle Fate", one of the many galleries the Etruscans excavated during their unremitting research of metals to manufacture.
The name of Montieri started to appear in documents since 973. In that year, it belonged to the imperial feudatory Lamberto degli Aldobrandeschi and it was ceded to the priest Ropprando. Both the names show the Lombard origin of the first seigniories of the territory. After the year 1000, the area became part of the properties of the bishopric of Volterra, but it had already become a target of the Sienese republic.
In the XII century, in effect, the Sienese started to mint their own currency and this led them to get interested in territories rich in precious metals such as Montieri. Therefore, the town was the object of a dispute between Siena, Massa Marittima and the curia of Volterra. The latter had been distracted by the clashes inside the group of the Pannocchieschi to which it belonged. The emperor Frederick II was involved in the disputes, too, but a real solution was found in 1326 with the annexation of Montieri to the Republic of Siena.
In the XIV century, John Hackwood's mercenary English troops assaulted and devastated this small fortified village. The town's inhabitants themselves rebuilt the stronghold and walls in 1371. Around the XV century, the slow decadence of the town started and its economic importance dependent upon the mines began to weaken in the years. At the half of the XVI century, Montieri entered the Grand Duchy of Tuscany after the Spaish and the Medici occupied the territories of Siena. Only some towers of the castle remained and one of them was the bell tower rising between the church and the Town Hall, and the donjon can be visible, too.