This continent has not seen a transformation like Detroit’s since the last days of the Maya. The city, once the fourth largest in the country, is now so depopulated that some stretches resemble the outlying farmland and others are altogether wild. Downtown still looks like a downtown, and all of those high-rise buildings still make an impressive skyline, but when you look closely at some of them, you can see trees growing out of the ledges and crevices, an invasive species from China known variously as the ghetto palm and the tree of heaven. Local wisdom has it that whenever a new building goes up, an older one will simply be abandoned, and the same rule applies to the blocks of new condos that have been dropped here and there among the ruins: why they were built in the first place in a city full of handsome old houses going to ruin has everything to do with the momentary whims of the real estate trade and nothing to do with the long-term survival of cities.

The transformation of the residential neighborhoods is more dramatic. On so many streets in so many neighborhoods, you see a house, a little shabby but well built and beautiful. Then another house. Then a few houses are missing, so thoroughly missing that no trace of foundation remains. Grass grows lushly, as though nothing had ever disturbed the pastoral verdure. Then there’s a house that’s charred and shattered, then a beautiful house, with gables and dormers and a porch, the kind of house a lot of Americans fantasize about owning. Then more green. This irregular pattern occurs mile after mile, through much of Detroit. You could be traveling down Wa bash Street on the west side of town or Pennsylvania or Fairview on the east side of town or around just about any part of the State Fair neighborhood on the city’s northern border. Between the half-erased neighborhoods are ruined factories, boarded-up warehouses, rows of storefronts bearing the traces of failed enterprise, and occasional solid blocks of new town houses that look as though they had been dropped in by helicopter. In the bereft zones, solitary figures wander slowly, as though in no hurry to get from one abandoned zone to the next. Some areas have been stripped entirely, and a weedy version of nature is returning. Just about a third of Detroit, some forty square miles, has evolved past decrepitude into vacancy and prairie—an urban void nearly the size of San Francisco.

It was tales of these ruins that originally drew me to the city a few years ago. My first visit began somberly enough, as I contemplated the great neoclassical edifice of the train station, designed by the same architects and completed the same year as Grand Central station in Manhattan. Grand Central thrives; this broken building stands alone just beyond the grim silence of Michigan Avenue and only half a mile from the abandoned Tiger Stadium. Rings of cyclone fence forbid exploration. The last train left on January 5, 1988— the day before Epiphany. The building has been so thoroughly gutted that on sunny days the light seems to come through the upper stories as though through a cheese grater; there is little left but concrete and stone. All the windows are smashed out. The copper pipes and wires, I was told, were torn out by the scavengers who harvest material from abandoned buildings around the city and hasten their decay.

On another visit, I took a long walk down a sunken railroad spur that, in more prosperous times, had been used to move goods from one factory to another. A lot of effort had gone into making the long channel of brick and concrete about twenty feet below the gently undulating surface of Detroit, and it had been abandoned a long time. Lush greenery grew along the tracks and up the walls, which were like a museum of spray-can art from the 1980s and 1990s. The weeds and beer cans and strangely apposite graffiti decrying the 1993 passage of the North American Free Trade Agreement seemed to go on forever.

I took many pictures on my visits to Detroit, but back home they just looked like snapshots of abandoned Nebraska farmhouses or small towns farther west on the Great Plains. Sometimes a burned-out house would stand next to a carefully tended twin, a monument to random fate; sometimes the rectilinear nature of city planning was barely perceptible, just the slightest traces of a grid fading into grassy fields accented with the occasional fire hydrant. One day after a brief thunderstorm, when the rain had cleared away and chunky white clouds dotted the sky, I wandered into a neighborhood, or rather a former neighborhood, of at least a dozen square blocks where trees of heaven waved their branches in the balmy air. Approximately one tattered charred house still stood per block. I could hear the buzzing of crickets or cicadas, and I felt as if I had traveled a thousand years into the future.

To say that much of Detroit is ?ruins is, of course, to say that some of it isn’t. There are stretches of Detroit that look like anywhere in the U.S.A.—blocks of town houses and new condos, a flush of gentility spreading around the Detroit Institute of Arts, a few older neighborhoods where everything is fine. If Detroit has become a fortress of urban poverty surrounded by suburban affluence, the city’s waterfront downtown has become something of a fortress within a fortress, with a convention center, a new ballpark, a new headquarters for General Motors, and a handful of casinos that were supposed to be the city’s economic salvation when they were built a decade ago. But that garrison will likely fend off time no better?than Fort Detroit or the?Hotel Pontchartrain.