The High Line was originally constructed in the 1930s, to lift dangerous freight trains off Manhattan's streets.
It runs from Gansevoort Street in the Meatpacking District to 34th Street, between 10th & 11th Avenues.
It was the inspiration for THE CURIOUS GARDEN by Peter Brown . Recently it inspired Tommy Kane's 500th blog post for Sugar Frosted Goodness.
Here's a map and a video of the park on opening day.
And here's a video: http://videos.nymag.com/video/Opening-Day-at-The-High-Line