Milano is served by five subway lines.

• Red Line M1: Sesto F.S. - Rho Fiera Milano / Bisceglie
• Green Line M2: Gessate / Cologno Nord - Assago Milanofiori Forum / P.za Abbiategrasso Chiesa Rossa
• Yellow Line M3: Comasina - San Donato
• Blue Line M4: Linate Airport - San Cristoforo
• Lilac Line M5: Bignami Parco Nord - San Siro Stadio

The system is supplemented by the Passante underground rail link which connects urban and suburban railway stations to the subway network. 

Here you can find complete info on operating hours and tickets of the underground system, trams and buses.