Line E of the Buenos Aires Underground runs from Retiro to Plaza de los Virreyes, a total distance of 12 km.

Line E was opened on 20 June 1944, after construction began in 1938, with an original route that ran from Constitución railway station to General Urquiza.

Work began in 1957, and in 1966 the San José, Independencia, Belgrano and Plaza de Mayo (now Bolívar) stations were opened to the public by president Arturo Umberto Illia.

[12] It is expected that with the line's extension to Retiro completed in 2019, the CAF GEE rolling stock will be retired and replaced by and possibly 50 Siemens O&K cars refurbished by the Emepa Group and Alstom.

[15] San José vieja was used as a set for the 1996 Argentine film Moebius and served as the fictional Dock Sud and Parque stations.