To spend five minutes chatting with Charles Birnbaum is to hear about dozens of tantalizing gardens—historic parks, regional estates, public plazas, private modernist gems—that, like Shangri-La, you’ll never lay eyes on. Landscape architect and founder of the Cultural Landscape Foundation—a repository of everything from oral histories to panoramic comparisons of places like Dan Kiley’s Miller Residence and Thomas Church’s Donnell Gardens—Birnbaum is a walking ency- clopedia of landscapes both extant and extinct. Describing a full-on assault on open space, the passionate preservationist explains how unique places once created for contemplation are being paved over or redesigned into “a pupu platter for the ADD generation—with dog walks, spray fountains, cafés, skateboard ramps,” and other distractions.

Of the more than 80,000 properties on the National Register of Historic Places, fewer than 1,900 are directly related to landscape architecture. And while a thousand of the buildings are less than 50 years old, maybe a handful of modern landscapes are similarly protected. Hence, at Kiley’s NationsBank Park Plaza in Tampa, Florida, for example, the dry, crumbling fountains remain as a kind of memento mori. “It’s ironic—the classic modern design blurred the boundaries between indoors and out, yet we’ll trash the landscape that was conceived as part of the whole,” muses Birnbaum, explaining that when a building makes it onto the registry, its surroundings usually don’t. It’s not that Neutra houses don’t get bulldozed. But with landscapes, the process is even more insidious, as years of overgrowth, lack of maintenance, and added features slowly but irrevocably transform the original.

Yet Birnbaum is no knee-jerk preservationist. “It’s not about maintaining landscapes under glass—places do and must evolve—but about intelligent rehabilitation that looks through the lens of the original designer. With a house, it’s understood you should know the history before you start overlaying features.” Nor is every project worth preserving. “[Lawrence] Halprin’s Nicollet Mall was totally unsuited to the Minnesota climate. But look at Fulton Mall in Fresno [California],” he says excitedly, referring to one of the first outdoor pedestrian malls in the United States, the 1964 collaboration between Garrett Eckbo and Victor Gruen that’s in need of restoration. “Or Sasaki and Dawson’s Christopher Columbus Waterfront Park in Boston—one of the very first revitalized waterfront parks in America. And it’s gone!”