The Jefferson National Expansion Memorial in St. Louis is the site of a modern icon--the Gateway Arch--and a historic 91-acre Dan Kiley landscape. But the site is throttled on all sides by a maze of infrastructure, turning it into an island that divides downtown St. Louis from the Mississippi River. The Michael Van Valkenburgh Associates team's winning proposal for the redesign of the Memorial site hews closely to the spirit of the Kiley landscape, but revitalizes it in order to reintroduce ecological diversity and function to the currently inert monoculture of lawn. The Memorial is a pilot project for a new kind of urban National Park, one that is oriented, physically and culturally, toward the life of the city, and one that pioneers new kinds of sustainable urban ecologies.