These free-roaming horses were once destined to disappear from the land.

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

In Tucson a giant metal snake helps pedestrians cross a busy highway.

This golf ball–shaped former desert real estate office now houses a UFO museum.

A working cattle ranch with remarkably well-preserved prehistoric petroglyphs and ancient ruins.

This Arizona observatory is famous for investigations into Martian life, and as the place humans first spotted Pluto.

Witnessing the might of this dessert-colored desert waterfall is a rare, powerful treat.

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

Eons ago, a rushing lava river formed this pristine passage through solid rock.

An arsenic-filled pool in the Grand Canyon takes on the appearance of a giant, overflowing pumpkin.

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."

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

A self-built castle made by a mysterious man.

An abandoned facility that has become a place of ritualistic satanic worship, or so rumor has it.

This secluded aqua waterfall in the Grand Canyon is the perfect swimming hole, and the Havasupai tribe's fiercely protected natural wonder.

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

A collection of haunted objects and macabre oddities under one roof.

Nevada's largest cactus collection stands outside a candy mogul's small factory.

Designed as a place for patients to take in the scenery, this tower has a dark history.

This path is named for a mythical half-boar, half-deer creature that once roamed the Green Mountains.

An ancient glacial pothole waterfall in the heart of the Green Mountains.

This cavernous abandoned marble mine is popular with ice skaters in the winter.

A popular 19th-century natural landmark is now hidden within a sprawling forest.