In the construction site orders of the sixteenth century, it is called with the name of Bastionedell'Annunziata or of Bastione of the Island. The denomination in the plural today commonlyused, together with the seven doors quote, it comes later, not earlier than the 17th century.
Although it was designed and built in the same years as the bastion of S. Maria (since 1525) witha project by the same Paduan technician Pietro Antonio Tomaselli, its setting on pentagonal plan clearly differentiates it from the other: there weren't the constraints that have conditioned the shape of the S. Maria, so that its design appears much more responsive to rules of the new fortification engineering.
Further enhancements will be adopted starting from 1533 with the arrival at the construction siteof the engineer Antonio Ferramolino, to whom we owe the changes in the two extremities: to protect the guns the gorges of the mumps open on the flanking line of the main curtain wall, and to a lesser extent, on the short horn of the opposite front facing north. Inside, the large rooms do not follow strict geometry rules. A ladder in a very steep slope leads to the winding gallery, created at the foot of the long rampart of the entire perimeter of its foundation.
Terranova C.P., La città murata. Dalla visita al "memorabile viaggio.", in Milazzo Nostra n. 28-29 - Marzo-Luglio 2011, pp. 22-23