 As of 2015, Buenos Aires is the only Argentine city with an underground metro system, nonetheless there is a project to build a system in the city of Córdoba (Córdoba Metro) making it the second underground system in Argentina.The Buenos Aires Underground (Subterráneo de Buenos Aires) has currently six lines, each labelled with a letter from A to H, though 3 more lines are planned.A modern tram line (PreMetro) line E2 works as a feeder to Underground Line E at their outer terminus as well as the Urquiza Line for Underground Line B in Chacarita.