Best Rooftop Urban Park New York 2000 - Dia Center for the Arts
Okay, so to call it a park may be a stretch, but it's an optical treat as entertaining as any fountain or path or jungle gym. The "park" project at Dia Center for the Arts was designed by Dan Graham and consists of a large glass sculpture, a café, and a "video salon." The sculpture, a cylindrical glass affair with revolving doors, plays tricks on the eyes, causing vision to jump around into disorienting 3-D reflections of the Manhattan skyline. The Dia Center, an interdisciplinary arts organization with a four-floor space in Chelsea, is equally worth visiting (and you'll have to, anyway, if you want to explore the roof).