
There are four underground/subway lines (#1 - red, #2 - green, #3 - yellow, #5 - purple ), one suburban rail link (AKA "Passante", (in blue on subway maps), and roughly 70 lines serviced by trams, trolleys, and buses. Buy your tickets, including daily passes, before boarding, and stamp them properly when you get on a bus, subway or tram. The inspectors do call, and they won’t care if you’re a tourist. They’ll bust you in Italian if they have to.