Only a short time after its opening, the ele-vated High Line Park, located on a disused freight-train viaduct in Manhattan, has became a true attraction, loved by architects, residents and tourists alike. In the following interview, Ricardo Scofidio, the architectural partner responsible for the scheme, and Matthew Johnson, the project architect in the New York office of Diller Scofidio + Renfro, describe the concept and planning.