Menaced by environmental problems, torn by struggles between the tiny coterie of wealthy Spaniards at the center and a teeming, fractious polyglot periphery, battered by a corrupt and inept civic and religious establishment, troubled by a past that it barely understood--to the contemporary eye, sixteenth- and seventeenth-century Mexico City looks oddly familiar. In its dystopic way, it was an amazingly contemporary place, unlike any other then on the planet. It was the first twenty-first-century city, the first of today's modern, globalized megalopolises.