Last month we walked the third (and newest) section of the High Line. We each had our favorites.
One of us really liked the playground (Pershing Square Beams) and could have crawled, clambered, and popped up into the single "gopher hole" for longer than we had time to spend at the park. Two other fun elements of the new section are the revealed rail tracks that you can walk on (Rail Track Walk) and the remnant rail equipment -- the rail "frog" and switches which you can play manipulate.
I enjoyed the rise and fall of the 11th Avenue Bridge and the Interim Walkway.
I never saw the High Line before it was developed into a park so I missed the seeing the complex of spontaneous vegetation that once covered the tracks. These hardy herbaceous perennials have been preserved -- for now at least I assume given that the walkway itself is billed as an interim space -- alongside the walkway. The vegetated trackbeds are the site of Adrian Villar Rojas' The Evolution of God, a land art installation commissioned by the High Line.
We found the cubes, constructed of cement and clay, endlessly fascinating. Each was filled with different types and configurations of natural and human-made objects. Each cube was in a different stage of decay. The juxtaposition of decaying art in the foreground and rising luxury in the background was riveting. A full description of the sculptures and Villar Rojas' biography are available on the High Line website.