Mammoth Cave, Kentucky
{"Image ImageDescription": "Mammoth Cave, Kentucky: The only subterranean spot on our list of top 10 natural wonders, Mammoth Cave is the largest known cave system on the planet. The natural labyrinth consists of nearly 400 explored miles of serpentine tunnels.", "Image Software": "Adobe Photoshop CS5 Macintosh", "Image Artist": "Adam Jones", "Image Copyright": "Adam Jones/Getty Images"}