Italy did not become a nation until about the mid nineteenth century. When that happened, instead of using the language of the largest city, or the dialect used by the most people as their national language, they decided to find the most beautiful dialect. The dialect the picked was the dialect used in Florence in the fourteenth century (which no one really spoke anymore). And not only that, they didn't exactly use the dialect spoken by everyday people on the street, but the language used by Dante Alighieri in his Divine Comedy. He used the vernacular, but shaped it as he wrote his masterpiece. As Elizabeth Gilbert writes in her memoir, Eat, Pray, Love, (which is great, by the way) it was as if "a group of Oxford dons had sat down one day in the early nineteenth century and decided that from this point forward-everybody in England was going to speak pure Shakespeare. And it actually worked."
Cool. Not that I'm going to learn Italian.