Monte Argentario was probably an island that gradually became joined to the main coast as the accumulated detritus deposited by rivers and the sea formed the two tombolos of the Feniglia and the Giannella. Archaeological finds from the Grotta degli Stretti and Cala dei Santi show that the area was settled by humans in very early times. At least 10 caves are known to have been lived in, one of which, the Grand Duke’s Cave (la Grotta del Granduca, named after Leopold of Lorraine who sponsored its excavation), is almost a mile in length and even has a small lake about 50 yards from the entrance. The peninsula was considered a safe haven by seamen on account of its geographical position in the centre of the Tyrrhenian Sea: it was also strategically placed and became the site of numerous look-out towers to give warning of impending danger from the sea. The threat of invasion was indeed constant and during one memorable incursion in 1544 the pirate Khair ad Din, known as Redbeard, plundered the village of Porto Ercole.
The earliest defence works date from the Bronze Age, but it was only in the XV century A.D. that the Senese Republic started to build a proper defence system encompassing the whole promontory. However, it was the Spanish who, in only a few years, transformed Monte Argentario with a powerful complex of military forts, far greater in number and effectiveness than any others in Tuscany. Thus was the Stato dei Presidi (literally, the Garrison State) founded; it included Orbetello, Porto Ercole, Porto Santo Stefano and Talamone. To these in 1602 was added the stronghold of Porto Longone on the island of Elba. The mountainous peninsula rises to a height of 635 m, and has a rocky coastline. The vegetation is mostly thick Mediterranean maquis alternating with olive groves, vineyards and fruit orchards: it is famous for the dwarf palm, which here grows wild. The rare Ansonico and Riminese varieties of grape are grown in terraced vineyards on the hillsides. Today tourism has replaced fishing as the principal economic activity of the area.

The picturesque town of Porto Ercole with its thriving tourist harbour lies on the eastern coast of Monte Argentario and is dominated by the massive Spanish forts. The nearby marina of Cala Galera attracts large numbers of yachts and pleasure boats with its excellent facilities. The origins and early history of Porto Ercole are hazy, but the name Ercole was probably used by the Etruscans. The recent discovery near Cala Galera of an Etruscan necropolis situated in the thirteenth sector of the Etruscan zodiac, corresponding to the constellation of Hercules, would appear to confirm this.
In the early Middle Ages it belonged to Three Fountains Abbey, together with the rest of the promontory. In the thirteenth century it became the property first of the Aldobrandeschi and then of the Orsini families, before falling to the Senese Republic in 1415. Under the Stato dei Presidi, in 1557, it formed the mainstay of the peninsula’s defence system with its imposing military forts. In 1610 the painter Michelangelo Merisi, better known as Caravaggio, died alone as a fugitive on a nearby beach, probably of malaria.

Situated on the north coast of Monte Argentario, Porto Santo Stefano is the largest town on the peninsula and its administrative centre, as well as a renowned tourist resort. The old and new harbours together are a hub for both business and tourist activities, including a fishing fleet, sailing and ferries linking the port with the islands of Giglio and Giannutri. There are also several small boatyards and shipwrights. The town first developed around the fort after the foundation of the Stato dei Presidi, especially under the governorship of Gilles Nunez Orejon. From the XVIII century onwards families of fishermen from Liguria and Naples started to settle in the town and their descendants still account for a sizeable portion of the population.

The town of Orbetello lies on a narrow tongue of land jutting out into the eastern and western lagoons and has been joined to the Monte Argentario promontory since 1841 by an artificial dyke. The two lagoons are closed by two strips of land, the tombolos of the Feniglia and the Giannella, offering several miles of beaches. Thanks to its unusual setting, the town appears from above like a ship anchored in the still waters of the lagoon, with the artificial dyke forming a gangplank linking it to the Argentario peninsula. The origins of the town and of its name, Orbetello, are unclear: Orvelus, Urva Tellus or Urbis Tellus - the circular town, the town of herbs or the town of towns? Perhaps if it had not been plundered in 1455 and the town’s archives destroyed we would know more.
From 1557 to 1801 was the capital of the Stato dei Presidi, until was annexed to Grand Duchy of Tuscany from Napoleon. At the beginning of the last century the town’s economy was still largely based on farming and fishing in the lagoon. The development of industry brought several factories, the mines, the hydro port and the fish processing plant. These industries transformed Orbetello into a busy and prosperous town that was dubbed “Little Venice” or “Little Paris”. It’s name is also linked to an important chapter in the history of Italian aviation. Four transatlantic hydroplane flights took off from the lagoon: from the first Atlantic crossing in 1928 to the last and most famous - Orbetello - Chicago - New York - Rome - in 1933.