 Writing in the mid-2nd century, the Greek astronomer and geographer Ptolemy wrote that "Bracara Augusta" had been under Roman rule.Archaeological work completed researchers from the University of Minho discovered a defensive wall, consisting of polygonal plan, reinforced by small semi-circular turrets, dating to the 3rd century.Recent information points to polygonal plan, defined by rectilinear lines that crossed the structure, with an area between 40 and 50 hectares, punctuated by semi-circular towers .