(from the article `Teotihuacán`) Along the southern part of the avenue lies the Ciudadela (`Citadel`), a large square courtyard covering 38 acres (15 hectares). Within the Citadel ...(from the article `pre-Columbian civilizations`) ...Chan. Chan Chan covered an area of about 14 square miles (36 square km), with a central area of about 2.5 square miles containing 10 or more large ...