Cartagena has had a long relationship with the macabre. In 1610, the city became the seat of the Spanish Inquisition in Latin America. Although never as bloody as its counterpart in Iberia, the Dominican-led push to root out heretics, witches, Jews, and other undesirables resulted in roughly seven hundred local persecutions and five autos-da-fé. The Inquisition Palace is a grand Andalusian-style building freshly restored as a museum on the north side of the Plaza de Bolívar. There's a display of torture racks, stockades, and a scale used to weigh women accused of witchcraft to see if they were light enough to fly. On the outside wall, at the height of a person on horseback, is the denunciation window. Here, seventeenth- and eighteenth-century Cartageños with a grudge would anonymously slip the names of heretics through the iron grille. Across from the window is another of Willy's friends, a vendor of pasteles de bocadillo—flaky triangles of pastry with a line of bocadillo jam on the end, the jam pale pink and tasting of guava.

I ask Willy if he knows everyone on the street. "Oh, sure," he says. "The city is my friend."

Founded in 1533 on a small Caribbean peninsula, Cartagena quickly became one of the most important cities in Spain's South American empire. Much of the gold, silver, emeralds, and pearls stolen from the Incas and other Andean civilizations passed through its warehouses. By the middle of the sixteenth century, nobility and merchants there were building Andalusian- and Moroccan-style palaces and mansions, all with elaborate courtyards hidden from the street by high wooden gates. The colonial administration put up stately public buildings and laid out plazas and squares, and the Catholic Church erected a soaring cathedral, churches, and many monasteries and convents, rivaling the throne for influence and wealth.

So much treasure was amassed in Cartagena that soon French and English pirates were attacking the city, looting the loot. Sir Francis Drake sacked the city in 1586 with twenty-five vessels and more than two thousand men, returning it to Spain for the ransom of 120,000 ducados. The Spanish built an elaborate complex of walls and forts, a project that lasted nearly two hundred years and required the labor of some eighty thousand slaves. It culminated in the Castillo de San Felipe, Spain's largest military fort in the Americas, an imposing structure that looks something like the pyramids outside Mexico City. It was designed with trapdoors, casamatas ("niches of death," Willy explains), and two thousand feet of internal tunnels, some of which deliberately lead nowhere. It and many of the city's other fortifications remain intact, including almost all of the walls that surround the historic neighborhoods where Willy presides with a handshake and a smile. The walls now make a scenic promenade. Along the way are a number of garrets that you can step into to look out at the Caribbean through a musket hole.