Buenos Aires  officially the Autonomous City of Buenos Aires, is the capital and primate city of Argentina. The city is located on the western shore of the Río de la Plata, on South America's southeastern coast. "Buenos Aires" can be translated as "fair winds" or "good airs", but the former was the meaning intended by the founders in the 16th century, by the use of the original name "Real de Nuestra Señora Santa María del Buen Ayre ", named after the Madonna of Bonaria in Sardinia, Italy.

The city of Buenos Aires is neither part of the province of Buenos Aires nor the capital of the province. Rather, it is an autonomous region. In 1880, after decades of political conflict, Buenos Aires was federalized and removed from the Province of Buenos Aires. Both are now city neighborhoods. A 1994 constitutional amendment granted the city autonomy, hence its official name is the Autonomous City of Buenos Aires. Its citizens first elected a head of state in 1996. Previously, the mayor was directly appointed by the President of Argentina.