First, we have already the Romans, which are what most italian nationalist stand for. And nowaday italian culture is a direct derivate of roman, french and spanish one, with a bit of everything else. Wait, look, french and spanish cultures are derivates of romans as well

I will call it fair and keep the romans.
Second, our contribution to history, as a 150 years old country, is... well, ludicrous. The best I could say about my country is that we are imaginative people, good lovers, excellent cooks and terrible soldiers, with the possible exception of Peacekeeping.
I do not want do do wrong to our [very fractured, very glorious] past but we stood as a land of conquest for many centuries. This disrupted our identity, greatly improved our cultural variety, greatly improved our literature and greatly destroyed any ambition on self-improvement in the typical italian.
True to be told, most Italians don't feel Italians, one way or the other. Most people argue about corruption, and then evade taxes. Most people say that nepotism is bad, that the so-called Barons of Medicine and university are an evil to be eradicated, and then go to the most influential neightbour to ask for a job.
To me, we're not an accomplished nation. We're a bunch of children kept together by some long-sought ideal, gathered a century ago by some lousy monarch with the help of powerful neightbours. We're more like a burocratic, stately held republic that runs under theocracy and caste system
Maybe, just maybe, in a century or so we will form a more stable nation or - as I hope - integrate in Europe with all other countries and local nationalism* will be forgot for good. One could dream
*: to non-italians: in Italy we keep a very strong prejudice, for good and for bad, about every region one come from, about the way one behave, think, work and relate to friends. Often it looks like we got no Italians, but instead piedmontese, emilians, sicilians and so on. If not worse and go for city provenience. Often people couldn't even write in a barely readable italian nor, in some places, speak it. Those are the basis on which stand our identity