The truth is probably a combination of these explanations and something else—luck, a political deal, the weather, who knows? For whatever reason, Cartagena has remained safe: For nearly two decades, it has been a haven for Colombia's middle and upper classes. The middle class came on holiday. The upper class brought architects and decorators and bought up a number of the crumbling mansions. Among a certain set, renovating a house in Cartagena implied social status. They whitewashed the stucco, repointed the coral stones, wrought the iron grilles, shored up the wood balconies, repaved the patios, turned on the water in the fountains, planted the bougainvillea. Historians like to talk about the unintended consequences of war. While civil war was ripping up much of Colombia, Cartagena was being restored.

There are two sides to Cartagena—the life on the street and the life behind the gate—and no place represents this better than the Plaza de Bolívar. Some of the city's most important buildings surround the plaza—the cathedral, the Inquisition Museum, the Gold Museum, the Central Bank. The plaza is a crossroads and a resting point. People traverse its paths as they go about their errands. Others stop to cool themselves near the fountains or on the benches under the palms and the rubber trees. Vendors sell coconut milk, orange water, peanuts, lollipops, cigarettes. One man has refitted a baby stroller into a coffee cart. I'd be exaggerating if I told you Willy knows everyone in the plaza. But he knows a good many, including the public historian who, according to Willy, stands on a box and recounts episodes of Cartagena's history for a few hundred pesos.

Willy works for the tourism ministry, guiding visitors around the city. He starts every day at the Jesuit cloister named for Saint Peter Claver, the seventeenth-century Spanish monk who baptized 150,000 slaves in the New World. On his deathbed in 1654, in a final act of humility, Peter Claver declared himself the "slave of slaves." In 1888, Pope Leo XIII canonized him—the first monk in the Western Hemisphere to be so designated. Saint Peter Claver is a revered figure in Cartagena. The understated church named for him has a subdued facade of coral stone, a butter-colored cupola visible from almost anywhere in the city, and tall doors that open at precise times of day. A couple of years ago, Willy tells me, six green parrots began visiting the bell tower every day at sunrise and sunset—an exoticism that feels like a flourish from a García Márquez story.

Willy is thirty-six, a trim, compact man who keeps fit by walking around the walled city. A former navigational officer in the Colombian Navy, he has a degree in history, a mind for dates, and a way of highlighting the memorable historical tidbit. This is evident when he ushers me over to Saint Peter Claver's glass and gold-leaf coffin. The saint's skull rests on a pillow. His other bones are in a white sack covered by a gold cassock. His remains are intact except for two bones: His femur resides in his hometown of Verdú, Spain; and in 1986 Pope John Paul II brought a piece of a finger bone back to Rome with him as a relic.