Buenos Aires has long been a magnet for immigrants. Successive waves of wanderers from Italy, Africa, Asia and elsewhere have washed up in that cosmopolitan city, and each group has brought a little taste of their homeland with them. And now we have all those tastes here in Denver at Buenos Aires Pizzeria, where Buenos Aires native Francis Carrera serves all the variegated flavors of his home town in pizza form. Skip the more traditional pies in favor of something unusual, something you've never had before -- hearts of palm, maybe, or a pie speckled with bits of hard-boiled egg. Then make a note to return for gnocchi night or one of the kitchen's excellent Cuban sandwiches.