South Bastion, Gibraltar

The South Bastion was part of the fortifications of Gibraltar, protecting the western base of the Charles V Wall. It was originally built by Spanish military engineers, later improved by the British. The South Bastion stands at the south end of the Line Wall Curtain which defends the town from attack from the Bay of Gibraltar. Another curtain wall runs east from the bastion to the base of a precipice. This wall is pierced by the Southport Gates, guarded by the South Bastion and the Flat Bastion on either side.

The Milanese military engineer Giovanni Battista Calvi visited Gibraltar in 1557 and drew plans for two defensive positions to the south of the town, where the South Bastion and Flat Bastion now stand, connected by a new curtain wall. Calvi was ill, and did not stay to carry out the planned works. It may have been another Italian, Amodeo Agostino, who died in 1571 who built the original bastions. Another source says the bastion that was incorporated into the South Bastion was probably designed for Philip II of Spain by the Italian engineer Giacomo Fratino in the 1560s.

The South Bastion, called the Baluarte de Nuestra Señora del Rosario ("Bastion of Our Lady of the Rosary") by the Spanish, had been built by 1627.[a] Casemented gun positions on the bastion enfiladed the ditch across the Gate of Africa, now the Southport Gate. The South bastion, and the Flat Bastion further inland, protected the Southport Gate, which lay between them.