Fortresses on the island of Sant’Andrea were for centuries the bulwark of the West in the face of Ottoman expansionism. The Turkish danger was, explicitly, the basis of the direct decision to fortify properly Brindisi. While the Turks were still barricaded in Otranto, in February 1481 Ferrante of Aragon ordered the start of work for the construction of a fortress guarding the port of Brindisi. In 1485 Alfonso, Duke of Calabria, transformed the tower of Ferrante into a real castle. It was then decided to isolate the rock with the cut of the rock and the opening of a canal. The castle, also known as the Red Castle due to its color at sunset, the carparo blocks with which it is built, is a masterpiece of defense architecture: the trapezoidal shape and the thick walls have made it impregnable for years. In 1558 the construction of the fort began, which will last for about forty-six years with the intervention of some of the most famous military architects of the time. The Aragonese canal was transformed into a quiet dock connecting the new and ancient structure.