Yes, well The Wilds is 10,000 acres in size, but it's not exactly a "zoo". You ride in a safari bus through much of it. There are three or four places where you can get off and walk around including the Medium Sized Carnivore Center, and you can also over look the park at the lodge. They also offer other activities such as mountain biking, hiking, and bird watching. They also have traditional Mongolian yurts and lodges and cabins where you can stay over a chosen period of time. I'm not sure if you can view the animals through those activities or not though.
"The Wilds" is mainly toured via a safari bus, and I visited Monarto Zoo in Australia in 2007 and a good chunk of that zoo is also seen via similar transportation. North Carolina Zoo is all on foot, which makes for a long and exhausting day. However, in terms of a strictly walk-through establishment it must be a strong contender for the largest zoo on the planet.
