Visitors to Italy tend to seek its sunny, Dionysian side – vino, pasta, opera, cinquecento art. But, like a chilly draft on a hot day, Italy’s Gothic angle offers intimations of darkness that make a moment on the piazza even more delicious. Consciously or not, anyone sipping prosecco at sunset in Rome or Naples savours an extra spoon of dolce in their vita thanks to the contrast between the beauty of the present and the proximity of catacombs, ruins and sites of ancient sufferings.

The original Gothic writers were much inspired by the duality in the bel paese. Edgar Allan Poe, Nathaniel Hawthorne, Horace Walpole, Ann Radcliffe and other masters of the romantic and horror genres set some of their most famous works in Italy.

“Italy was the Gothic writers’ favourite background,” wrote Massimiliano Demata, a professor at the University of Bari, who has made a study of the form. The country’s baroque portas, ruined castles, eerie reliquaries and catacombs were a gateway to the uncanny, possessing, as he put it, “a labyrinthine and claustrophobic architecture that was the novels’ perfect physical and psychological setting.” Today, these same books can serve as unconventional guidebooks for tourists who tire of the sun and want to explore the country’s macabre past.

For the Gothic writers, different locations in Italy piqued different aspects of the imagination. Venice seemed to hold special appeal for those wishing to mine pre-Freudian psychological terror. I decided to start my tour in Otranto, a white, cobbled seaside town on the Adriatic edge of Italy’s boot heel and the setting for what’s regarded as the first Gothic novel, “The Castle of Otranto” by Walpole. I had visited the town briefly one summer afternoon with children in tow. Returning in late fall, I found the formerly bustling streets chilly and silent – not as inviting, perhaps, but more in keeping with the intimations of its macabre history that I had been reading about in guidebooks.

Otranto, I had learned, is literally haunted by an old act of evil: a 15th-Century massacre – one in the long and bloody skirmish between Islam and Christianity – that Otrantans commemorate annually to this day.

“Local history is filled with blood and darkness,” an Otranto guide and historian, Francesco Calignano, told me as he led me into the Cathedral of Otranto.

The cathedral is known for its complex mosaic floor, which depicts scenes from just about every human myth and legend known to the world circa AD 1100, including kabbalah’s tree of life, Confucianism and Puss in Boots.

We entered on a raw, late-autumn morning, and we were the only people inside. After admiring the beautiful floor, I was led to a truly Gothic spectacle: Lining shelves on a wall off to the side were 800 human skulls – victims of invading Turks. Calignano grimaced as he related how bits of the victims’ preserved flesh are still stored in a locked drawer. Once a year in August they are removed and paraded through town streets.

“The Castle of Otranto” was a publishing phenomenon in 1764. Walpole’s short tale describes the supernatural punishment of a usurping Italian feudal prince in a haunted castle packed with what we now consider standard fright stock – secret doors, gloomy tunnels, haunted suits of armour, portraits of ancestors jumping out of their frames. At the time, though, these images were so fresh and shocking that Walpole’s little book became an instant best seller in England.

Modern-day Otranto is a place of seductive pleasures, where a warm afternoon can be passed bathing in azure seas and gorging on nouvelle Italian seafood accompanied by the crisp local Greco di Tufo wine. I paid a few euros and toured the castle’s white corridors alone, seeking signs of Walpole’s ghosts, peering into small, empty, barred rooms, any one of which could have been a dungeon. On the outside, it is a photogenic and perfectly preserved white fortress. But its turrets, gunwales and wide, waterless moat attest to the inhabitants’ defensive terror of the invader hundreds of years ago.

A short flight or a five-hour train trip west across the heel of Italy to Naples allows ample time to dig into the works of a lesser-known Gothic master, Radcliffe. She was a reclusive Englishwoman who like Walpole was celebrated in her day for novels, many of which were set in Italy, that pit seemingly supernatural forces of evil, often associated with Catholicism or small-time feudal tyrants, against guileless young women and their brave, thwarted lovers.

Radcliffe’s best-known novel, “The Italian,” takes place in 18th-Century Naples. Almost every page contains a castle keep, a shadowy ruin and creepy, robed stalkers from the religious orders. The plot is simple enough: A young nobleman of Naples falls in love with a girl of whom his mother strongly disapproves. The mother hires an evil monk to do away with her, but the monk discovers that the girl is actually his daughter – the product of an illicit affair.

The novel opens with an Englishman surveying the Naples church of Santa Maria del Pianto, which Radcliffe wrote housed “the very ancient convent of the order of the Black Penitents.”

Contemporary visitors can test Radcliffe’s Gothic imagination against the lively reality of the teeming city. The church of Santa Maria del Pianto is still there, but it’s not on any tourist map.

It does still exist, but in what is now an organised-crime-infested suburb called Secondigliano. I crossed it off the to-do list, reluctantly.

Radcliffe’s other Neapolitan sites are worth a visit, if only because searching for them allows one to wander the city’s streets, noting the many other Gothic charms of Naples that Radcliffe missed.

The book’s lovers, Vivaldi and Ellena, first lay eyes on each other at the church of San Lorenzo Maggiore, which still stands in Naples’ historic centre – a yellow and gray hulk with an archaeological site underneath it.

Rome is rife with Gothic locations, and for my trip I took along “The Marble Faun,” by Hawthorne. Hawthorne was reaching the end of his career as a master of the psychological and supernatural horrors of Puritan New England, and this novelistic travelogue is not his best. A two-volume compendium of some of the eerie sites, it is a meandering tale of three American artists working in Rome who meet and befriend a real-life satyr, who seems to have been the flesh-and-blood model for a marble statue in the Capitol.

Visitors to the gloriously treasure-packed Capitoline Museums today will find many statues of the faun, associated with Dionysus, who represented the animal in man, simultaneously innocent, sexual and lawless. The faun’s more threatening relative, the satyr, is overtly Luciferian, with horns and cloven hooves. A large satyr of this type glares archly out from a cupboard in the Egyptian courtyard of the museum.

A bus ride or a leisurely stroll across Rome’s historic centre leads the traveller to another principal site in “The Marble Faun” – the creepily gorgeous Capuchin Catacombs, where the Hawthorne characters confronted an evil monk.

Decorated in Baroque style with the white bones of 4,000 dead monks, the Capuchin Crypt near the luxurious Via Veneto is today a popular stop on any Rome tour. As macabre as it seems, it’s also a sacred site. No cameras, no hats and no summery clothes are allowed.

“Tell the Americans, no spaghetti strap trash,” said Alba, the stern receptionist on duty the afternoon I was there, while berating a group of Germans who were ignoring the signs about turning off their cell phones. “Listen,” she exhorted them in English. “The cellphone lines are too strong for the human bones here. They are really delicate.”

The crypt is tiny and claustrophobic, and the bones’ sickly sweet smell fills a dimly lighted passageway winding past eight gated displays with arabesques of thousands of bones arranged by type – fingers, patellas, femurs, knuckles, skulls – in lacy flowers, garlands, clocks or urns, attached to walls and ceiling. In the final room, the message posted on the floor near the roses strewn by worshippers, in five languages, reminds happy tourists to drink deeply from the cup of Italy’s joys now, as the eternal shadow looms: “What you are now we used to be. What we are now you will be.”

Back upstairs and on the streets of Rome, the pleasures of Italy are immediate and accessible, but also complex. Without the darkness, the country might be as bland as Sweden. Looking at Italy through the Gothic lens deepens our appreciation of the pain, suffering and death that is, along with love, ease and light, also man’s lot. The hellward pull of Thanatos on Italy’s Eros, the artful dance between these archetypal opposites, is surely one of Italy’s great enchantments.