first in Latin America, the Southern Hemisphere and the Hispanophone world, followed by the Madrid Metro in 1919. The network was originally built and operated by three separate private companies and later nationalised in 1939. In 1952 it was absorbed by a unified state administration, in 1963 it became the property of a newly founded company, which changed hands in 1979. The Subte then entered into a concession model in the mid-1990s through which private sector parties were to submit bids to execute investment plans "designed and funded" by the state, while implemented by the concessionaire. All the Underground lines, along with the Urquiza Line and Premetro were offered as 20-year concessions to interested private parties. By 1995, Metrovías took over the Subte under a $395 million plan. Early days Discussions on the need to build an underground transportation system in Buenos Aires began in the late nineteenth century, alongside the tramway system, which was one of the most extensive in the world at the time. The first trams appeared in 1870, and by about 1900 the system was in a crisis exacerbated by the monopolisation of the lines, which had concentrated under the ownership of fewer companies during the electrification of the system. In this context, the first proposals for the building of an underground system were made, along with requests for government grants: first, in 1886, and several more in 1889. However, the Ministry of Interior (Ministerio del Interior, in Spanish) denied the city administration the power to license building in the city's subsoil and for this reason, subsequent drafts were submitted directly to this ministry. In 1894, when it was decided to construct the Congress building in its present location, the underground idea was revived, since it would shorten the travel time between the Casa Rosada and the Congress. In 1896 Miguel Cané, former Mayor of Buenos Aires (1892–1893), expressed the need to build an underground railway similar to the one in London There were numerous proposals at the time to build an electric aerial tramway, with one such line to go down the Avenida de Mayo. One proposal was the 1889 Le Tellier proposal, which envisioned multiple lines running along the city's wider avenues with the trams moved using cables and would hang from steel rails fixed to steel and iron posts positioned in intervals. The lines would take 24 months to build, and construction would