City Park is the 6th largest and 7th most visited in the United States. It is twice as large as NY's Central Park and home to the largest collection of mature live Oak trees in the world, some of which are 600-700 years old.
Much of the park was destroyed by Katrina, but most of it has come back. But the old City Park golf course remains untouched to this day. Plans are in the works to bring two pro quality courses back to the park, but who knows what will happen in these economic times. Check out a master plan here.
For now, the abandoned courses at City Park offer quite the terrain for exploring, bike riding, jogging, camping...whatever. Check it out sometime.