I went to Milano in November. Well today it arrived the ticket that I entered an area where I should not be. Its quite common here in Italy that in some areas of big, even small cities you have a zone where only the people who live there can enter (by car). There must had been some signs there about not being allowed to enter. But I was way too concentrated to watch the road and that sign for sure was a bit "hidden".
Any way, you need a permit to enter there and of course to obtain that permit you have to pay (even the folks born there) but this applies only to vehicles. For example where I live, in the center of the town, I had to pay 25 euros so I can drive 500 meters to park my car in my condo. You just have to pay it once, then you receive a card saying you are resident here, this is your car, plate number and are authorized drive around