From a 1985 interview with Italo Calvino, found in Hermit in Paris (2003, tr. Martin McLaughlin):
You would like me to mention some book I read as an adolescent and which subsequently made its influence felt in things I later wrote. I will say at once: Ippolito Nievo’s Le confessioni di un ottogenario (Confessions of an Octogenarian), the only Italian nineteenth-century novel which had a novelistic charm that was comparable to that found so abundantly in foreign literatures.
What I am pretty sure Calvino meant was the kind of foreign books boys like: Treasure Island and Poe and The Count of Monte Cristo, books I have seen Calvino mention elsewhere as favorite childhood reading. The Nievo novel he loves, then, is likely a partial one, the novel of the kitchen boy in the crumbling castle.
An episode in my first novel, The Path to the Spiders’ Nests , was inspired by the meeting of Carlino and Spaccafumo [the bandit]. An atmosphere vaguely reminiscent of the Castello in Fratta is evoked in The Cloven Viscount . And The Baron in the Trees  reworks Nievo’s novel around the protagonist’s entire life, and it covers the same historical period, straddling the eighteenth and nineteenth centuries, and the same social environments; moreover, the female character in my novel is modelled on Nievo’s La Pisana. (240, everything in brackets are my insertions)
Calvino has mentioned his first three novels. I doubt any other writer has made such through use of Nievo. I reread Path and Viscount to see for myself, but actually before I came across this interview, and the connections were obvious. The Path to the Nest of Spiders, as translator Archibald Colquhoun called it, is a realistic novel about a band of misfit anti-Nazi partisans operating in the woods of Calvino’s native Liguria. It is told from the point of view of a boy, a ruffian, too young to understand women or politics or even violence, really, so a good outsider. His name is Pin, so he is a protagonist like Kipling’s Kim (mentioned by name on p. 105) or Huck Finn or Jim (Hawkins). Or Pinocchio. It is only that one scene that looked like a direct nod to Nievo, where Pin, like Carlino, is lost in the woods and is guided to safety by a misfit, a smuggler in Nievo, a partisan in Calvino.
The tone of The Clove Viscount could hardly be more different. The title character is split in half by a Turkish cannonball, one side purely good, the other evil. The evil side returns to his castle to terrorize his subjects. The narrator is an eight year-old boy, a neglected nephew of the Viscount – so now we are in Nievo’s world. Little action takes place in the castle itself, but rather everywhere in the surrounding countryside, the woods and hills. I am getting more of a hint about what part of Confessions Calvino really liked. The Baron in the Trees, which I have not read for twenty-five years, is also almost completely set outdoors (see title).
I had forgotten how comically disgusting The Cloven Viscount was, how many mutilated corpses of men and animals, casual murders, and disfiguring diseases were featured, all for a laugh along with details like the bride who “still had a few yards of veil left, [so] she made a wedding robe for the goat and a wedding dress for the duck, and so ran through the woods, followed by her two pets, until the veil got all torn in the branches and her train gathered every pine cone and chestnut husk drying along the paths.” (240)
I had thought about writing a bit about Giuseppe Tomasi di Lampedusa’s The Leopard (1958), in which the author reaches back a century to describe the moment his family’s world was demolished by Garibaldi’s invasion of Sicily (by his side, Ippolito Nievo, who had just written Confessions). But it is so obvious, right? Manzoni, Nievo, Lampedusa, all following the same strategy. Lampedusa also stole Nievo’s dog. Lampedusa made some improvements, but the death of the dog in Confessions is a fine scene.
Nievo played the same game. The great recurring guest star in Confessions, aside from Napoleon, first seen getting a haircut, is the radical Italian nationalist poet Ugo Foscolo, who plays apart in the overthrow of the Venetian Republic. Nievo’s novel is even more packed with collapses, suicides, and weeping than The Last Letters of Jacopo Ortis. It has more weeping men, actually, than any non-Japanese novel I have ever read. Foscolo’s novel is a blatant imitation of Goethe. Etc. etc. etc. It is all one great chain of books if you want to look at it that way.