May 17, 2006—It's one of the most breathtaking spectacles in the U.S.—the colorful chasms of the Grand Canyon. But could this natural wonder become a victim of its own popularity? In 2005 Grand Canyon National Park hosted nearly 4.5 million visitors—double the number that visited in 1974.

Take a tour of this stunning natural landmark, and learn about the growing threats to the canyon's rugged but delicate beauty.