Following the coastline of Formentera you will find five defense towers that were built in the XVIII century to protect the island against pirates. They´re part of a network of towers used to establish visual communication between the most strategic points of the island. To communicate between towers during the day they used smoke and at night they used fire and were prepared to incorporate artillery to serve not only as watch towers but also as active defense towers although finally artillery proceeding from the Sant Francesc Xavier church was only installed in the Es Cap de Barbaria and Es Pi des Català towers. This defense system guaranteed the safety of the population during the XVII and XVIII centuries favoring the demographic growth of the population of Eivissa, and contributing to the consolidation of the process of repopulation of Formentera started at the end of the XVII century.