Chief mountain system of Mexico, consisting of three ranges, the Sierra Madre Oriental, the Sierra Madre del Sur, and the Sierra Madre Occidental, enclosing the central plateau of the country; the highest peak is Citlaltepetl at 5,700 m/18,700 ft. The Sierra Madre del Sur (of the south) runs along the southwest Pacific coast.
The emblem reflects the Vatican's importance as the headquarters of the Roman Catholic Church. The colours of the flag are based on the gold and silver of the papal keys. Effective date: 8 June 1929.