The seven current bastions were ordered to be built by king Felipe II, following the traces of engineers Juan Bautista Calvi between the years 1554-1576, and Jacobo Frantin between the years 1576-1588.

The enclosed space inside the walls was developed during the confrontation between the Spanish crown with France and the Ottoman Empire, during which the islands were ransacked by the Turkish and their allies. That is why in the beginning they thought to reinforce the medieval defensive walls but due to the intensity of the attacks they opted to create defensive walls against artillery.

Nowadays, the defensive walls take up the highest area of the city, approximately 10 hectares and around 1800m of perimeter, and they have become the most important monument in the island.

The fortification must be understood as a military machine, as a very sophisticated architectural organism. The materials used were stone, mares stone and stone slabs, with different types of grouting always using lime mortars and earth fillings with earth on the inner face of the walls and bastions, all of them functioning as retaining walls.

Our intervention becomes completely transparent, without undermining the essence of the monument

The project documents the conservation state of the walls and, from that information, reintegrates the parts that are missing, filling the gaps and cracks, and eliminating the vegetal elements.