delegación (legation), central Distrito Federal (Federal District), central Mexico. At 1,425 feet (2,294 metres) above sea level in the Valley of Mexico, it is on the northeastern slopes of the extinct Cerro Ajusco volcano. In the district are remains of a pre-Columbian town, and 1.5 miles (2.5 km) west of Tlalpan is the Cuicuilco Pyramid, construction of which began in early prehistory and was completed by 300 BC, when a village developed around it. During the colonial era the settlement was called San Agustín de las Cuevas, named for the church of the same name (1532). Given city status in 1827, Tlalpan served as capital of México state from 1827 to 1830. It retains a traditional and tranquil atmosphere, with large residences, health care institutions, and rehabilitation centres. Because of its proximity to central Mexico City, which lies approximately 12.5 miles (20 km) to the north-northeast, Tlalpan is easily accessible by highway, railroad, and air. Pop. (2000) 581,781.