The oldest subway system in South America, the first line was opened to the public in 1913. You can still ride cars dating from that era on the original line (Linea A). For information on the public bus sytem, please see this page.

As of June 2014, fares are ARS$5.00 and allow unlimited transfers between lines. Pre-paid Subte cards are purchased at the ticket booth (boleteria) or self service dispensers located at the entrance to the station. You can purchase these cards for multiple journeys, but there will be no savings.

Assorted Subte cards:
 

There is also a stored value debit card called SUBE which can be used on either the Subte or buses.  The SUBE card costs ARS$25 to purchase and you can add value to the card at many stores displaying the SUBE sign, or at the subway station ticket booths.  When using the SUBE card to pay for the Subte, the fare is discounted to ARS$4.50. Buying a SUBE card is a bit tricky. Stations don't sell one. You have to find a right store. There are many stores that show the SUBE sign but many of them only add values to SUBE cards. You have to ask around to find a store who sells cards. A store with serious dividing plastic windows to talk to the agents is a good sign, but some are just like other kiosks.

Street entrances to the system are well marked and very visible. There are usually various entrances from nearby points that lead to the same station.

A typical Subte entrance:
 

A typical carriage at Catedral Station on Linea D:
 

Retiro Railway Station is accessed by the Subte station of the same name on Linea C:
 

Subway service on most lines begins at 5 AM and ends before 11 PM. Sunday service begins only at 8 AM.
 
Lines A, B, D, E roughly follow a north-south trajectory that begins in Centro and spreads out to the outer barrios. Line C follows Av. 9 de Julio and serves as a connector to the others. Line H is soon to be completed and will serve as an additional connector line further uptown and allow passengers to do a limited circle trip without having to travel back downtown to connect with line C.

The Buenos Aires Subte system was privatized in the early 1990's and is now run more efficiently by Metrovías. Their website can be viewed in English and they have useful features such as maps and schedules interspersed with a lot of information not particularly useful to most commuters. The map page has some interactive features that are very useful in helping plan a trip within the city.

Some useful stations:

Plaza de Mayo (Linea A): Plaza de Mayo, Casa Rosada, Parque Colon.

Saenz Peña (Linea A): Shopping on Av de Mayo, Edificio Barolo, Plaza de los Congresos, Madres de Plaza de Mayo.

Congreso (Linea A): Congreso Nacional, shopping on Av Callao and/or Rivadavia.

Retiro (Linea C): Retiro Train Station, Omnibus Terminal, Torre de los Ingleses, Sheraton Hotel and Towers.

San Martin (Linea C): Plaza San Martin, shopping on Av Santa Fe and Florida, Marriott Plaza Hotel, American Express office.

San Juan (Linea C): Closest (6 blocks) to San Telmo's Plaza Dorrego.

Tribunales (Linea D): Teatro Colon, Palacio de Justicia.

Pueyrredon (Linea D): Shopping on Av Santa Fe and/or Pueyrredon, German Hospital, and closest (10 blocks) to Recoleta Cemetary.

Plaza Italia (Linea D): Plaza Italia, Buenos Aires Zoo, Botanical Garden, Sociedad Rural, shopping on Av Santa Fe and/or Las Heras.

Carlos Pellegrini (Linea B): Obelisco, shopping on Av Corrientes, 9 de Julio and/or Carlos Pelligrini.

Alem (Linea B): Puerto Madero, Luna Park, shopping on Av Corrientes.

Carlos Gardel (Linea B): Abasto Shopping Centre, shopping on Av Corrientes.

Federico Lacroze (Linea B): Chacarita Cemetary