[Reily]

Modern Italian is primarily the Tuscan dialect. I think it was Mussolini who decided to base modern Italian around Tuscan. In southern Italy the Italian has a lot of Greek words in it that go back to the day - Pre-Roman days where the area was Magna Graecia - an area of Greek colonies.

[Verginius Rufus]

Actually I had heard that the reason that Tuscan became the basis for the standard language is Dante and the prestige he lent to his native dialect with The Divine Comedy. Mussolini is too recent.

There are actually a few villages in southern Italy where the local dialect is a form of Greek. Parts of southern Italy remained under Byzantine rule until 1071.

There are also a few places where the local dialect is Albanian or Croatian (descended from refugees from the Turkish conquest of the Balkans), and a few places along the Slovenian border where the locals speak Slovenian. And of course in the South Tyrol the locals speak German.