From the site www.reciproca.it, text by Enzo Velati:

“The large number of coastal towers that now dot the historical memories coast development of the beaches and cliffs of Puglia is a surprise for those who follow modern roads on the sea, making the circumnavigation of Gargano, ranging from Termoli to Margherita di Savoia.
All these towers are located in scenic spots: they were once used to control the coasts and with their presence they remind us of times when the sea was not a friendly presence but a dangerous gap open for pirates and privateers who periodically raided on our slaves and collected coasts .
Look-out posts have always existed, ever since the prehistoric age, but what we now call the Saracen towers date back to 1500 and nearly all of them come from Puglia being chosen as a bulwark of the Kingdom of Naples against the Turks.
Just to let your imagination travel, think of Vieste being sacked back in 1480, during the massacre of Otranto, then in 1554 (5,000 people were killed, when the fame of the “Bitter Chianca” ­- the rock on which people were beheaded – was born) and again in 1674 and 1678.
Since 1532 and for over 200 years this chain of towers was built to promptly notify the nearest towns of the approaching danger.
Each tower had to see the other two, and the alarm was given with great fires or horns and bells. As a rule they did not serve as a shelter, and few people lived there. In 1748 there were 25 in”Capitanata”, and most of them were built between 1568 and 1569, when the senior official of the court of Naples, Alfonso Salazar, visited the region and ordered the construction of 21 towers to Giovanni della Monica. That’s why most Gargano towers are quadrangular truncated pyramids and the slope of the walls ends in a crown which has four or five trapdoors on each side.
The access to the towers was high with retractable wooden ladders, later replaced by masonry ramps. Some of such towers are still intact:  Torre Mileto among the lakes of Lesina and Varano, Torre Rivoli north of Zapponeta; many other (Sfinale, Calalunga, Portonuovo, S. Felice, Petra Tower, Monte Pucci) have lost the crown due to events over time or have seen it replaced by more modern superstructures that allow them to be livable.
The oldest towers, probably from the end of XIII century, are the ones at the mouth of the East Lake Varano: cylindrical, they have Ghibellines (dovetail) battlements, very rare in our region. ”