It is probable that at the beginning Monte Argentario was an island subsequently "anchored" to the Tyrrhenian coast by sand-and-gravel bars of Feniglia and Gianella, formed by the deposit accumulations transported by rivers and marine streams.

The first human settlement certainly goes back to remote periods. This is proved by numerous archaeological finds from Grotta degli Stretti and Cala dei Santi. There are at least 19 of the caves that were inhabited. One of them is very capacious: Grotta del Granduca, over 1 km long, called so in honour of Leopoldo of Lorena who promoted the excavations. 50 metres from its entrance there is a lake.

The first navigators considered Argentario as a secure landing. This was due to its geographic position in the centre of the Tyrrhenian Sea. The promontory equipped by towers for sighting and signalling had an extraordinary strategic role. It helped to face the constant danger of the sea raids. The mostly remembered pirate is Khar ad Din also called Barbarossa who in 1544 robbed and plundered the coast of Porto Ercole. The very first defensive works date back to the Bronze Age. However, a true defensive system that interested the entire coast of Promontory began to take a form only in the XV century, under the power of the Republic of Siena. The Spaniards, in few years, succeeded to transform Monte Argentario into a powerful war machine. It was created to make an entire complex, which was remarkable for the number and quality that was superior to anything similar existing in Tuscany. It was thus born the State of Garrisons, that included Orbetello, Porto Ercole, Porto St. Stefano and Talamone, to which, in 1602 was added the stronghold of Porto Longone of the island of Elba.

The Promontory, entirely mountainous (m.635) and distinguished by high and rocky coasts, is covered by a thick Mediterranean bush alternating by the olive trees cultivation, vineyards and fruit trees. You can find here the dwarf palm (Palma nana) spontaneously growing everywhere. The vineyards, laboriously cultivated at the steep terraces, contain rare vine varieties, such as Ansonico and Riminese. The economy of Argentario, which was based exclusively on fishing, counts on tourism as the major income source.