Porto Santo Stefan and Porto Ercole are the two most important places in Mount Argentario with a population of about 13,000 inhabitants. The towers that stand out on the slopes of the homonym mountain show the strategic position that the town has had in the centuries. The convent of the Noviziato and the church of San Rocco can be admired in this town.

The territory of Monte Argentario is a peninsula rich in coves and beaches that once was supposedly an island and that later was linked to the coast thanks to the sedimentations produced by the rivers Feniglia and Giannella. Its caves were inhabited in Prehistory and, in the ancient times, the silors of the Tyrrhenian Sea chose the area to build ports well equipped to defend the ships calling from pirates.
The toponym of the town was due to the Roman domination of the Domizi Enobarbi who worked as "argentarii", that is to say as creditors. They owned the villa of Santa Liberata, called Villa Domizia. In the II century b.C., the area changed its name in "Insula Matidae" for the presence of a new ruler, Viba Matidia. Only from the V century on, the name "Mons Argentariorum" appeared in the writings of Rutilio Nomaziano.
During the Barbarian incursions, the depopulation of the Aurelia way and the paludification of the coast isolated the Argentario from the rest of Tuscany. At that time, the population, therefore, was administered autonomously, even if it was formally under the control of the Abbey of the Tre Fontane.
Later, the Aldobrandeschi, the Orsini of Sovana, the kingdom of Naples, and, since 1410, the Republic of Siena, ruled the promontory. Even if the Etruscans had already begun the fortification of the ports of the Mount Argentario and then the Sienese continued it the most important defence structures were carried out from the XVI century on. In effect, at that time, the raids of the pirates of Khair ad Din, the famous pirate "Redbeard", scared the populations of the area.
The Spanish realized the main defence complex. Between the XVI and the XVII the Spanish monarchy founded the "Stato dei Presidi" in the area which included Orbetello, Porto Ercole, Porto Santo Stefano and Talamone and the fortress of Longone in the Elba Island in 1602. The aim of this territorial nucleus was to garrison an important passage area of the Spanish ships by offering safe landing places on the route that links Spain to its satellite Kingdom of Naples.
Under the Spanish dominion, the Argentario started a period of development thanks to the fortresses of Porto Ercole and Porto Santo Stefano, above all. Families of Spanish soldiers and numerous fishermen communities from Liguria and Naples who had been attracted by the richness of the area and by the safety the Spanish guaranteed settled the area in this period. At the beginning of the XIX century, the Napoleonic troops occupied all the territories of the "Stato dei Presidi" and this meant the Spanish had to leave the area definitively. The Congress of Vienna in 1815 assigned the lands of the Argentario to the Grand Duchy of Tuscany.