The Passante Ferroviario di Milano is an underground railway which runs through Milan, Italy.

[3] Its main feature is to be open in its extremities, and to be directly interconnected with the railway system of Lombardy.

"Passante" is the Italian word for "passing" and is used to describe a railway built through a major city, connecting suburban lines.

The idea of a suburban railway network for the city of Milan can be traced back to the 1960s, when the increasing population of the city and the surrounding boroughs made clear the need for a faster and more efficient way to complete medium to longer distance journeys.

[4] Actual work proceeded very slowly, taking 15 years just to open the first part of the track from Bovisa to Porta Venezia.