The quickest way into Centro is by subte. For Microcentro, get off at Florida (Línea B) or Lavalle (C). Retiro and Plaza San Martín have eponymous stations on Línea C. Stations Avenida de Mayo (A), Catedral (D), and Bolívar (E) all serve Plaza de Mayo. Línea A has stops along de Mayo, including at Congreso. Lines B, C, and D intersect at Carlos Pellegrini/Diagonal Norte/9 de Julio. Change lines here only if you're going more than one stop. Otherwise, walking is quicker. Puerto Madero is close to L. N. Alem on Línea A, and is connected by the Tren del Este, a light-rail service running parallel to Avenida Alicia Moreau de Justo.
You can take a taxi or bus to Microcentro, but walking is the best way to move within it. Bus nos. 17, 24, 28, and 59 run between San Telmo and Microcentro; nos. 17 and 59 also stop in Recoleta and Palermo, while No. 24 continues on to Almagro. Bus No. 29 starts in La Boca and passes San Telmo and Centro before moving on to Almagro and Palermo. Bus No. 130 connects Centro with the southern end of Puerto Madero.