The Buenos Aires Underground, locally known as Subte, is a rapid transit system that serves the area of the city of Buenos Aires, Argentina. The first section of this network opened in 1913, making it the 13th earliest subway network in the world and the first underground railway in Latin America, the Southern Hemisphere, and the Spanish-speaking world, with the Madrid Metro opening five years later, in 1919. As of 2023, Buenos Aires is the only Argentine city with a metro system.

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" 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 (GaWC) 2020 ranking.