Located at:
Sand Canyon and Marine Way in Irvine
(866) 829-3829
Located on the grounds of the former El Toro Marine Base, the Orange County Great Park is the first great metropolitan park in this area. The park is still in the works, but you can get an idea of this massive project (Projected to be larger than Central Park in New York) by taking a ride on the Great Park Balloon, basically an observation deck that rises to about 500ft above the area.
I love to go here often.