Line E of the Buenos Aires Underground runs from Retiro to Plaza de los Virreyes, a total distance of 12 km. Opened in 1944, the Line E was the last completely new line to be added to the Buenos Aires Underground, until 2007 when Line H was opened. The line has a history of being re-routed and extended due to having been historically the line with the lowest passenger numbers on the network.

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.