I mentioned the Cafe Gambrinus a couple of images back; it's a historic coffeehouse that we would come to visit a couple of days hence. It's also a tourist trap, but it is indeed a historic place, once haunted by the likes of Filippo Tommaso Marinetti (founder of the Futurist movement and an enthusiastic supporter of fascism), Oscar Wilde, Ernest Hemingway and Jean-Paul Sartre.
And on 1 January 2002, the then Italian president Carlo Ciampi apparently spent the first euro there after Italy's admission to the euro zone. (Which I personally suspect is the cause of many of Italy's current economic problems, but that's a different discussion.)
Regardless, it does have a nice "nightlife vibe" about it.