Castelo de San Martín in Ares, Galicia, is a 16th-century coastal fortress built as part of the defensive battery protecting the Ría de Ferrol. Named after Martín de Padilla, an adelantado of Castile, the castle was strategically positioned alongside Castelo de San Felipe and Castelo da Palma to form the renowned "triangle of fire." The three fortifications controlled passage through the ría using a floating chain system, with San Martín equipped with eleven cannons capable of firing 600 meters to 1.5 kilometers. Though abandoned and in ruins since the 19th century, a lighthouse now occupies the site, continuing its role as a coastal navigation marker.
