Porto Ercole is now the second largest urban center of the promontory with about 5000 inhabitants.
The history of Porto Ercole seems older than his neighbor, already starting with the Etruscans, where a town was transformed into a harbor by the Romans.
Porto Ercole is mentioned in the Middle Ages in a donation of Charlemagne to the abbey of Tre Fontane. In 1296 Aldobrandeschi Margaret, Countess of Sovane, built a square tower which became the center of the fortress of Porto Ercole.
In the fourteenth century, the territory of the Orsini who inherited agandirent buildings.
In the fifteenth century, the port was bought by the powerful Republic of Siena, who built the walls that still surround the city (including the Gothic portal surmounted by a steeple) and built coastal towers.
Porto Ercole, was in the midst of the conflict between France and Spain for their claims on the Italian territory. A great battle took place there, the alliance between Florence and Spain, the Sienese with France.
The latter were defeated, and the port was attached to the Spanish Kingdom of Presidi which strengthened the promontory forts.
Under Spanish rule Porto Ercole has experienced its greatest prosperity by becoming a European port.
On 18 July 1610, Caravaggio died here.
With the dissolution of the State of Presidi by Napoleon, the city has experienced a slow decline.
The port is reborn as a tourist destination, with today places like Fort Forte Stella, churches of Saint Erasmus and Saint-Roch, walls, etc.