Old elevated train track that's been turned into a walking park through Meatpacking and Chelsea. Timed free tickets needed for weekends only, tickets not needed during the week.
New 'floating' park on the Hudson 2 blocks from Gansevoort. Need to book Free timed tickets.
Highest outdoor skydeck on the 100th floor in Hudson Yards. Need to buy tickets.
Old Nabisco factory that's full of shops and restaurants!