The Milan Metro is the largest rapid transit system in Italy in terms of length, number of stations and ridership; and the fifth longest in the European Union and the eighth in the Europe.

The architectural project of the Milan Metro, created by Franco Albini and Franca Helg, and the signs, designed by Bob Noorda, received the Compasso d'Oro award in 1964.

[7] The first projects for a subway line in Milan were drawn up in 1914 and 1925, following the examples of underground transport networks in other European cities such as London and Paris.

Planning proceeded in 1938 for the construction of a system of 7 lines, but this too halted after the start of World War II and due to lack of funds.

[8] On 3 July 1952, the city administration voted for a project of a metro system[9] and on 6 October 1955, a new company, Metropolitana Milanese, was created to manage the construction of the new infrastructure.

The first section from Lotto to Sesto Marelli (21 stations) was opened on 1 November 1964 after 7 years of construction works.

Two trains adorned with Italian flags left at 10.41 a.m. and arrived at the Sesto Marelli terminus at 11.15 a.m., greeted by the notes of the national anthem and the triumphal march of Giuseppe Verdi's opera "Aida".

The metro replaced several interurban tramroutes of the original Società Trazione Elettrica Lombarda (STEL) tramlines, in particular the Line 2 to Gessate.

[18] Beside Milan, 13 other neighbouring municipalities are served: Assago, Bussero, Cassina de' Pecchi, Cernusco sul Naviglio, Cologno Monzese, Gessate, Gorgonzola, Pero, Rho, San Donato Milanese, Segrate, Sesto San Giovanni, Vimodrone.

All the stations are provided with LED screens showing the destination and waiting time of coming trains.

[31] M5 stations Segesta and San Siro Ippodromo typically close after events at nearby Meazza Stadium to avoid passenger congestion.

Driverless rolling stock on M4 and M5 allow for more frequent service, with headways as low as ninety seconds during peak hours.

The bus service follows roughly the same route and stops at the same stations of the metro for most of the central part.

For M1 the night bus service its divided in 3 lines and continues to Baggio, well over the metro path.

An extension of Line 1 from Sesto 1º Maggio to Cinisello/Monza, towards the city of Cinisello Balsamo, is currently under construction.

[33] There is a project for a further 3 km extension of Line 1 to the west into Baggio, a neighbourhood on the eastern border of the municipality.