The High Line was formerly a rail track, which went out of use in 1980. It was abandoned for a long time before being converted into one of NYCity’s best parks. It now runs from Gansevoort in the Meatpacking District to up to 34th near the Javits Center. You can walk it in either direction, but as Rick Darke mentions in the podcast, it was intended to be walked from South to North.
Construction of Section 1 began in 2006 & the landscaping started in 2008. The last and most northerly section, “The High Line at the Rail Yards” up at 33rd St was completed in 2014.
Friends of the High Line, a community-based non-profit group, formed in 1999. They advocated for the line's preservation and reuse as public open space, so that it would become an elevated park or greenway.Their website (www.thehighline.org) is a wonderful resource, showing events, tours, art exhibits, music events etc. One of the nicest parts is its monthly Bloom List which describes what plants to look for on the various sections of the trail.
Piet Oudolf the Garden Designer and Rick Darke, Landscape Consultant published an account of the garden and its design in June 2017.
Rick Darke, the landscape architect was interviews on NPR's weekly series "Cultivating Place: Conversations on Natural History and the Human Impulse to Garden."
You can hear that interview in this link:
https://www.npr.org/podcasts/503170304/cultivating-place-conversations-on-natural-history-and-the-human-impulse-to-garden