It is not that I made a mistake of driving on pedestrian path

. At the entrance of the road, there will be a shield with ZTL etc., in square shaped.(ofcourse written in Italien) I am not the only who got punished like that.
There are quite a many around who had this bad experience. One of the forum where I saw people experiencing same problem. FYI:
http://www.digitalvoodoo.de/blog/reisen/teure-strafzettel-aus-florenz-european-municipality-outsourcing-eintreiben-bussgeld-aus-italien.php
If one is aware of this information, definitely we might pay attention but if we don't at all that such thing exist, then obviously we don't really pay attention as a foreigner or guest to that town. As our first priority is to spend timing in visiting places around

.
As mentioned, the roads are in town. On highways (autobahn), we pay toll but not in town to my knowledge. I do bought toll on autobahn. But the above mentioned problem is in town.
"Unauthorized" means: Only registered vechicles are allowed to go through that roads. something similar to bewohner here in Germany. If in case, we have to park in park house of that street or hotel is in that street, we have to give our car numbers to the owners so that they will pass on to their local adminstration and such that ,we are authorized. And we wouldn't get that surprise bills.
You might be lucky or without knowingly you did not passed that street for good.
Here is the example of one road:
http://maps.google.de/maps?f=d&source=s_d&saddr=43.766922,11.262032&daddr=&hl=de&geocode=&mra=dme&mrcr=0&mrsp=0&sz=18&sll=43.76741,11.262349&sspn=0.001662,0.003439&ie=UTF8&z=18
Check out in street view.
Hope this helps. Any questions, feel free to drop in.
Regards,
RK