An architect's childhood fantasy treehouse made real.

One of nature's most well-scheduled phenomenons resides in Wyoming's Yellowstone National Park.

The ancient dwellings of the Puebloans, located in the cliffs of majestic mesas.

A house carved into a rock in the 1940s.

One of the world's largest telescopes, stares into the night sky with two huge mirrors.

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

A Hawaiian stairway to heaven—that you can't climb.

This famous bridge twisted itself into oblivion, but not for the reason you might think.

The only structure left with direct ties to the Salem witchcraft trials of 1692.

The world's largest mountain carving could fit all of Mount Rushmore inside it many times over.

Twenty-seven massive radio antennas on the high plains of New Mexico search for life on other planets.

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

What is the Thing?

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

Most-visited and most-photographed slot canyon in the American Southwest.

The world's largest military aircraft cemetery.

A reproduction of earth's many biomes.

An old saloon in the West filled with history, and according to some, a few dozen ghosts.

The biggest solar telescope in the world helps reveal the secrets of our sun.

A spiritual vortex among the red rocks in Sedona.

America's only nuclear missile silo open to the public.

Sacred Buddhist home of some spiritual monkeys.

A sharp bend in a dramatic river canyon cut through red rocks.