The Cottonera Lines was one of the largest project of military architecture undertaken by the knights of Malta, and encircled the three old cities and the Margarita Lines.

The original intention to protect The Three Cities and their old landward fortification was to erect a fort in the countryside beyond.  Designed by the papal engineer, Vincenzo Maculano da Firenzuola in the first half of the seventeenth century, it was to have consisted of a long front of three bastions, with two somewhat antiquated round towers replacing bastions at the rear.  The Cottonera Lines get their name after the Grandmaster Nicolas Cotoner and this site and foundations were later used by the British upon which to construct the entrench work, Fort Verdala.