The Grand Canyon of Texas.

A phenomenal assembly of pueblos in New Mexico is the most complete example of ancient ruins north of the border.

The only diamond mine in the world where you can keep what you find.

Canyon walls shrouded in ferns.

A mysterious castle built as a monument to lost love.

A sculpture made of 10 Cadillacs as a monument to the “Golden Age” of the American automobile.

Home to the largest urban bat colony in North America, estimated at 1.5 million bats.

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

The world's longest known cave system.

The second-largest cave chamber in the world was discovered in 1898 by a 16-year-old and a friend known as "Pothead."

Ninety feet off the valley floor is an ancient dwelling put under protection of the U.S. government by Teddy Roosevelt.

The deepest lake in the United States, and once the site of epic destruction that lives on in legends.

An emerald-green grotto just a short trip from Austin.

The fairy tale castle of the “fairy-tale king,” this was also the inspiration for Disney’s “Sleeping Beauty.”