Some of the tallest ancient American ruins continue to inspire awe and curiosity.

Limestone caves with spectacular showcase chambers.

Ancestral Puebloan ruins, natural arches, and box canyons abound in this seldom-visited corner of Monument Valley Navajo Tribal Park.

Miniature art that tells an enormous story.

The Magical World of George Phar Legler.

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

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

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

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

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

A reproduction of earth's many biomes.

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

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

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

The installation’s official name, “You Who Are Getting Obliterated in the Dancing Swarm of Fireflies,” says it all.

Dramatic river bend surrounds a natural red-rocked pedestal.

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

A research lab and hands-on museum where visitors can experiment with retro technology.

This 19th century jail was mainly used to incarcerate the drunk and disorderly.

The oldest operating cemetery in Denver is the eternal home of some of the Centennial State's most famous residents.

There are eight natural springs around town, each with a slightly different taste.

An enthusiastically interactive mining museum that won't let black lung ruin the fun.

This museum offers an actual time machine back through Colorado's past.

This deserted Gold Rush town is home to a Masonic lodge that, strangely enough, still holds meetings.