In Cartagena, you never feel far away from the “magic realism” made famous by Colombia’s most famous son, the Nobel prize-winning writer Gabriel GarcÍa Márquez. Even at the breakfast table, bizarre and colourful things happen – a toucan landed one morning, snatched my bread roll in its kaleidoscopic bill, and hopped on to a banana palm to gorge itself.

Cartagena is the setting for the film of GarcÍa Márquez’s novel Love in the Time of Cholera, to be released in January, and directed by Mike Newell. With luck, the seductive setting of this romantic tale will reawaken interest in this lovely city.

Colombia certainly needs a bit of good PR. The distinctly ugly realism of internal conflict and drug trafficking has ruined the country’s appeal for tourists for many years now. It hasn’t quite endured one hundred years of solitude but it might just as well have been gripped by cholera.

However, a government-sponsored campaign aimed at boosting the country’s image has seen the number of visitors rise by 15 per cent this year. It’s now hoped that the film, starring Javier Bardem and Giovanna Mezzo-giorno, will further soften Colombia’s dangerous reputation.

Cartagena is a passionate Caribbean city – and the perfect backdrop for Márquez’s allegorical love story tracing Florentino Ariza’s obsessive love for Fermina Daza. By day, the pretty streets of El Centro district’s vividly colourful churches and townhouses pulsate to the fusion of Cartagena’s Latino, Mulatto and Afro-Car-ibbean populations. By night, in delicious half-lit shadows, sounds of salsa and vallenato and the clip-clopping of horse-drawn carriages echo in the streets. The old city is encircled by formidable 16th-century defensive walls built to keep English pirates at bay.

Ten years ago, a visitor would have found a far edgier place. I was advised then not to stray too far from my hotel at night. Perhaps at this time it was “the ruined city and its moth-eaten glories” that GarcÍa Márquez describes in his novel. But nowadays spas, sushi bars, pavement cafés and beautifully renovated boutique hotels (my own a former convent) are breathing new life into the once decaying 16th and 17th-century architecture of the Americas’ most complete colonial city. The most pressing nightly concern now is whether tuna teriyaki or Thai-style langoustines best accompany margaritas.

“Gabo certainly intended the story to be set in Cartagena,” says his brother Jaime GarcÍa Márquez, “it’s just that he has a way of taking real people and places and twisting them.” We meet in Plaza Santo Domingo by a corpulent Beryl Cook-esque statue of a renowned local prostitute called Gertrude.

Jaime takes me on a walking tour of locations that Márquez had in mind when writing the book. Plaza de los Coches, a broad colonnaded square, overlooked by a peach-coloured clock tower, is the “arcade of scribes” where lovelorn Florentino wrote amorous poetry; then Parque Fernández de Madrid Real (Parque de los Evangelos), a park of tamarind trees where Florentino kept vigil outside Fermina’s house each day. “Their story is based on our parents’ romance,” reveals Jaime. “My mother told Gabo, ‘I know you are writing about us, and I forbid it,’ but he went ahead anyway.”

The 16th-century Convent of San Pedro Claver, which features heavily in the film, is now a museum. Behind the pitted coralline-block façade is a brooding but brilliant assemblage of Jesuit art. But I wondered what pious San Pedro, his bleached skull poking through powder-blue robes inside a glass casket under the altar, would have made of a Hollywood film crew?

For devotees of Márquez, Cartagena is the start of an emerging literary trail around Colombia’s northern Caribbean coast. At Aracataca, where GarcÍa Márquez was born, a small museum dedicated to the writer is being completed. I caught a taxi one-hour westwards to Barranquilla, gradually watching Cartagena’s sun-drenched beaches empty of condos and revert to their pristine beauty, inhabited chiefly by pelicans.

Barranquilla inspired many of GarcÍa Márquez’s locations and characters as he worked there for years as a struggling journalist. I sought out his favourite restaurant-bar, the superb seafood grill La Cueva. He spent many nights there with some of Colombia’s great contemporary literary and artistic figures, such as Alejandro Obregón and the painter Ramón Vinyes; friends who became the inspiration for characters in One Hundred Years of Solitude.

Visit this part of Colombia and that beguiling, imagined world really does become magically real.

Need to know

Mark Stratton travelled with Proexport-Colombia Tourist Office (020-7431 4045, www.colombiaespasion.com).

Getting there: Air France (0870 1424343, www.airfrance.co.uk) flies from Heathrow to Bogotá via Paris from £712.10 return. Avianca (0845 8387941, www.avianca.co.uk) flies from Bogotá to Cartagena from about £200 return.

Staying: Sofitel Hotel Santa Clara (00 57 5 664 6070, www.hotelsantaclara.com) is a converted 17th-century convent with spa. B&B doubles from £147. La Passion (00 57 5 664 8605, www.lapassionhotel.com) is a beautiful eight-room boutique hotel. B&B doubles from £97.

Reading: Love in the Time of Cholera by Gabriel GarcÍa Márquez (Penguin Books, £7.99).

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