The castle of Scarlino has quite a remote origin if we consider the origin of its name from the Lombard tongue, according to many researchers. In effect, the name "Scarlino" could derive from "scherl" that means "lookout-post" in the tongue of this Barbarian population. Therefore, alredy in the Early Middle Ages, the fortress had a remarkable importance from a strategic point of view thanks to its position overlooking the valley, on one side, and the coast of Piombino, on the other.

The development of this fortress was consequential to the process of depopulation of the plain of Maremma. The abandonment of the countryside and the resulting paludification of Maremma, in effect, led its inhabitants to take refuge on the more healthful and safer hills. The castle had already been raised 973 and at the time it belonged to the Aldobrandeschi, the most important family in Maremma of Lombard origins. Later, there were many changes of ownership.
Te modern architecture of the castle of Scarlino dates to the XIII century. These were the years when the Republic of Pisa substituted the Aldobrandeschi of Sovana by taking the fortress and restructuring most of it. Thanks to the stronghold, the castle got the name of "Rocca Pisana". It has a five-sided layout and it is linked to the town walls. Numerous parts of the walls can still be seen as well as the Porta Senese and two of the keeps on top of the hill that have always given onto the stronghold.
Not all the sides of the castle are protected by towers. The two more external sides have their defences predisposed inside the walls and they are protected by a sort of wide ditch. Instead, the other two sides also have towers. Since they are the sides that face the sea it can be inferred that the towers were used as lookout-posts that patrolled the coast from top of the hill, as in particular it was the used of the more squared and higher Southeastern tower.
The North-western tower, instead, is more recent as its round structure predisposed for the use of artillery shows. The storage tank is kept inside the castle. Other elements were modified because during the pacification of Maremma the castle became a graveyard. Only the recent restructuring has made it fit for use and, today, the castle of Scarlino houses shows and cultural events.