An Italian address ends with a five-digit CAP, the town, and the province as a two-letter code in brackets — 20121 Milano (MI). The bracketed code is not optional formatting. Italy has thousands of comuni and a great many share names, so the province abbreviation is what makes the last line unambiguous, and it is the first thing an international form drops because it has no field for it.
The street line follows the German pattern rather than the English one: the street type and name come first and the number follows — Via Roma 12. Italian addresses also frequently carry an internal reference after the number, and buildings in older towns can use a separate red-and-black numbering system for commercial and residential premises on the same street, which is why an Italian address sometimes carries a letter beside the number.
The Italian telephone rule is the one worth putting in a test suite, and this site's own numbering-plan data records it as the well-known exception: Italy has no trunk prefix, so a landline's leading zero is part of the number and is retained in international format. Rome is +39 06, not +39 6. Every generic "strip the leading zero before adding the country code" routine corrupts Italian landlines, and because the result still looks like a phone number, nothing complains. Mobile numbers never begin with zero, so a rule that strips it damages exactly half the country's numbers.
An honest limit, since this page is about getting Italy right: the underlying locale library produces malformed Italian phone numbers — we have measured it emitting a Thai country code — so this generator drops the international format for most Italian records rather than publishing a number it cannot stand behind. The address is pinned to one of 15 real Italian cities with a genuine CAP; the phone field is where Italy is weakest here, and the methodology page says so.