Near the mouth of the Albegna River, on the left shore, the Forte delle Saline is a defensive architectural complex built in the second half of the 15th century. Restored several times since, it is indicated by nineteenth-century historian and naturalist Emanuele Repetti as "Torre delle Saline" with the function of Fort and Customs House. The name of the tower derives from the presence in this area of numerous salterns, which thus imposed the necessity to defend the site, as it was also the point of embarkation of grains from inland Maremma.

The complex is made up of a four-sided compound composed of a thick curtain wall with quite a wide parapet walkway, so as to leave room for the artillery. At the four corners are: the robust tower facing the sea, a small bastion in the opposite corner, and two other bastions with circular sentry boxes (one with cupola roofing, the other unroofed). The base of the compound has sloping walls reinforced at the corners and marked by a stone belt-course. The outwardly projecting tower has a height three times that of the enclosure and, at the peak, a series of arches on corbels. Forte delle Saline is therefore something of a hybrid between the tall, medieval-style tower and the low, robust curtain walls in response to the introduction of the cannon to the art of war, which prescribed the construction of architectural structures resistant to enemy fire, and able to permit cannons to fire at eye level.

The building inside the enclosure was used as a barracks of the Guardia di Finanza until 1962. Today, the entire complex is private property and serves as a private residence.