American bison herd descending directly from a Bronx Zoo breeding program that saved the species from extinction.

400 million-year old limestone caverns nestled in the Ozarks served as shelter and a hideout for cultures throughout North American history.

See massive fossils that are over 200 million years old in northeastern Arizona.

This 4,000-foot-diameter hole is touted as "the most well known, best preserved meteorite crater on Earth."