The Republic of Genoa built the watchtower of Santa Maria di a Chjapella in 1549, and about 100 nearly identical others, in the north coast of Corsica, so that the people could be alerted of Saracen attacks originating from the Barbary Coast. When the alarm rang, the Corsicans ran up to hideouts in the mountains. Those who couldn't escape on time were destined for the slave markets of Tripoli or Istanbul.
Peregrinus at anchor to the left of the watchtower. Rade de Santa Maria, between Punta Vecchia and the Finocchiarola Islands, in the north of Corsica. iPhone 6 Plus, 30 July 2016.