A melon can cost a hundred dollars; most Angolans make less than two dollars a day. Illustration by Emiliano Ponzi

Earlier this year, I was invited to a barbecue at the home of a Texas oilman, Steve Espinosa, and his wife, Norma. Their two-story house sat on an unnamed road, nestled in a community called the Condominio Riviera Atlantico, about ten miles from Luanda, the rapidly expanding capital of Angola. There were no sidewalks or footpaths in the area, and there wasn’t much movement on the street. But there were plenty of cars: Porsche Cayennes, Audis, and BMWs, all tucked neatly into identical carports adjacent to identical houses. Espinosa, a burly man in cargo shorts and a Brooklyn Industries T-shirt, answered the door and held out a beer. He steered me through a sparsely furnished living room, past a humidor filled with Cuban cigars, and onto the patio, where several of his friends and colleagues were snacking amiably on ostrich meat. There was a second kitchen beside the pool in the back yard, with a sink, a large refrigerator, and a Weber grill.

For the past two years, Luanda—not Tokyo, Moscow, or Hong Kong—has been named, by the global consulting firm Mercer, as the world’s most expensive city for expatriates. Luanda’s lure, and its treasure, is oil. José Eduardo dos Santos, who has presided over Angola for more than thirty-five years, long ago realized that foreign oil companies were the key to power, and he has worked diligently to accommodate them. In the past decade, tens of thousands of American and European employees of international oil conglomerates, fortified by generous cost-of-living allowances, have descended on Luanda. (Multinational companies base their overseas salaries on the comparative costs of housing, clothes, food, and other commodities.)

The country now produces 1.8 million barrels of oil a day; in Africa, only Nigeria produces and exports more. The boom has transformed a failed state into one of the world’s fastest-growing economies. Exxon-Mobil, Chevron, the French company Total, and BP all have significant operations in Angola, along with firms—Schlumberger and Halliburton among them—that provide the complicated logistical support required to drill and maintain deep offshore wells. Most of the foreign workers live with their families in well-guarded suburban communities with names such as Bella Vista and Paraíso Riviera.

At the height of the British Empire, colonial rulers lived by a credo: “Make the world England.’’ The oil expatriates of Luanda have taken that message to heart. Few would work there if they couldn’t live as they do at home, but their comforts have been hard to come by. Almost nothing is made in Angola, so nearly every car, computer, crate of oranges, tin of caviar, jar of peanut butter, pair of bluejeans, and bottle of wine arrives by boat. Every day, a trail of container ships backs up from the port through the Bay of Luanda and out into the sea.

Grotesque inequality long ago became a principal characteristic of the world’s biggest and most crowded cities. But there is no place quite like Luanda, where the Espinosas’ rent is sixteen thousand dollars a month, a bottle of Coke can sell for ten dollars, and Range Rovers cost twice their sticker price. Per-capita income in Angola has nearly tripled in the past dozen years, and the country’s assets grew from three billion dollars to sixty-two billion dollars. Nonetheless, by nearly every accepted measure, Angola remains one of the world’s least-developed nations. Half of Angolans live on less than two dollars a day, infant mortality rates are among the highest in the world, and the average life expectancy—fifty-two—is among the lowest. Obtaining water is a burden even for the rich, and only forty per cent of the population has regular access to electricity. (For those who do, a generator is essential, as power fails constantly.) Nearly half the population is undernourished, rural sanitation facilities are rare, malaria accounts for more than a quarter of all childhood deaths, and easily preventable diarrheal diseases such as rotavirus are common.

Because the oil companies routinely pay most large expenses for their foreign workers in Angola, a dollar bill can quickly begin to feel like Monopoly money. Before I visited the Espinosas, I asked at my hotel if it could provide a car and driver for the ten-mile journey from the center of the city to the suburb of Talatona. The clerk at the front desk told me it would cost a hundred and fifty dollars. There weren’t many alternatives, so I agreed. Later, I saw him waving frantically at me in the lobby. He explained that he had been wrong about the taxi: it would actually cost four hundred and fifty dollars, each way. I found another ride.

The trip took two hours. It was a Friday afternoon, and the single rutted road that runs south toward Luanda Sul was jammed with commuters, trucks, tractors, and a stream of the unregulated Toyota minivans—candongueiros—that pass for public transportation. Children worked the roadway, selling soccer balls, popcorn, phone cards, toilet seats, and multicolored polyester brooms. I stopped at the Casa dos Frescos, a grocery store favored by expatriates, to buy some Scotch for my hosts, but a fifth of the Balvenie cost three hundred dollars, so I settled for a mediocre bottle of wine, for sixty-five. The woman in front of me, juggling an infant and a cell phone, unloaded her groceries on the checkout counter. She had a couple of steaks, a few pantry items, and two seventeen-dollar pints of Häagen-Dazs ice cream, along with juice and vegetables. The bill was eleven hundred and fifty dollars. She didn’t seem fazed, and I later learned that the store was famous for its prices. A few years ago, the Casa dos Frescos had been the site of what locals refer to as “the incident of the golden melon.’’ An enraged French customer, having paid a hundred and five dollars for a single melon, sued the store for profiteering. The case was thrown out of court, in part because the man not only bought the melon but also ate the evidence.

For dinner, Espinosa grilled steak and part of a thirty-five-pound tuna that he’d caught the previous week on the Kwanza River. When oil people leave Angola, he told me, they often sell their freezers, packed with American beef, to their successors. “People can charge ten thousand dollars for a well-stocked freezer,’’ he said. He mentioned that a friend once tried to sell him a roll of aluminum foil for a hundred and forty dollars. Espinosa grinned and rolled his eyes. “That crazy Randy,’’ he said. “In the end, I think I paid thirty dollars.’’

“T.I.A., man,’’ he said, shrugging his shoulders and using a favorite acronym: “This is Angola.”

Angola endured four centuries of servitude and slavery before gaining independence, in 1975, and Luanda was once the world’s busiest slave port. The National Museum of Slavery, about an hour from the city, is housed in a spare colonial structure that sits on a promontory overlooking the Kwanza River. There isn’t much to see—drawings of slaves crammed into steerage for the trip across the Atlantic, a display of shackles, and some brief historical notes—but the simplicity is powerful and disturbing. The building is the last place that slaves came before they were blessed by a priest, put on a boat, and shipped to the markets of Rio de Janeiro, New Orleans, and the Dominican Republic. Millions passed through the region, many of whom died before they reached their destination.