Buenos Aires is the capital city of Argentina, on the western shore of the Río de la Plata on South America's southeastern coast. "Buenos aire…Buenos Aires is the capital city of Argentina, on the western shore of the Río de la Plata on South America's southeastern coast. "Buenos aires" is Spanish for "fair winds" or "good airs". Buenos Aires is classified as an Alpha global city, according to the Globalization and World Cities Research Network 2020 ranking.