New Orleans is smaller and poorer than it used to be, as I have confirmed on my first visit there since the floods attendant on Hurricane Katrina obliterated a large part of the city and left much of the rest a mud-gray mess, traces of which aren’t hard to find, three years later. I went to review “Prospect.1,” the inaugural New Orleans Biennial, which represents eighty-one artists from thirty-four countries in about thirty ad-hoc locations, and which took the whole of a three-day sojourn to explore in full. (A car is essential.) Some of the offerings are keenly rewarding, but the best thing about the show is the sprawl, which affords a wide and deep immersion in the city’s complicated charms. Be it ever so small and poor, and despite catastrophic displacements, New Orleans can’t help but remain New Orleans, which is to other cities what a poem is to prose. The phantasmagoria of high and vernacular architecture, polyglot flavors, omnipresent music, exuberant cemeteries, and geographical unlikelihood, of a seaport largely below sea level, stokes continual wonderment. Desire isn’t only a street name there. A municipal tradition of giddy impulsiveness, shadowed by recent tragedy and chronic woes—including a high incidence of crime—has got to many of the invited artists in “Prospect.1.” In the friskily hyperbolic words of a review by Walter Robinson, the editor of Artnet Magazine, the show “takes the reprobate scallywag nihilists of the contemporary avant-garde and converts them … into goody-two-shoes bleeding-heart believers in the nobility of humankind.” You may disdain the frequent sentimentality in the show if you can suppress your own uprushes of sentiment. I could not.