The Republic of Siena had expanded westwards to the sea in the 12th and 13th century and built a series of watchtowers and forts along the coast to defend against pirate raids. The towers were used for communication between troops, early warning lookouts, and defensive battlements. There are twelve such towers in the Maremma National Park, none with a greater story than the Bella Marsilia tower on a bluff looking out to the sea and Argentario beyond.

In 1543, the beautiful daughter of the rich Marsili family was kidnapped from the castle here by the pirate Barbarossa and sold to Sultan Suleiman in Constantinople. She became renown as the most beautiful and intelligent of his harem wives, bore him children, but never returned. Legend says you can see her striking red hair in the sunset from at the top of the tower.