This canyon is named for a unique geologic formation where the river vanishes underground near the mouth of the canyon and reappears farther down.

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

The largest hot spring in the United States is, as the name suggests, a stunning show of natural color.

A beautiful geyser under environmental threat.

A life-size bronze statue of Ettore Boiardi, the man behind the can.

An experimental, automotive replica of Stonehenge.

This erect, phallic geological spire wasn't always named so domestically.

From this scenic rockface, you can still see the paths Western pioneers followed.

An ordinary rancher stumbled upon one of the world’s largest collections of Pliocene horse fossils.

During World War II, over 13,000 people of Japanese ancestry were forcibly removed from their homes and incarcerated in this camp in the Idaho desert.

The only bridge in the United States where BASE jumping is legal without a permit year-round.

This underground cave located in the most barren reaches of Idaho is filled with ice year-round.

These falls, sometimes called the "Niagara of the West," still put on a good show at the right time of year.

Home to the deepest rift anywhere on Earth.

This coastal port saw one of the most significant battles of the Civil War.

A group of monuments to the Cherokee origins of Tennessee.

This lavish abode was once the home of the inventor of "Gorilla Pants."

Known by many as once the world's smartest horse.

The physical legacy of one man’s lifetime mission, following a near-fatal mine accident, to publicly proselytize for Christianity.

Supplies are schlepped up by llamas at this century-old inn, accessible only by hiking trails in the Great Smokies.

Built in the 19th century, this bucket has been to two World’s Fairs.

The former home of the 11th president of the United States.

Waterfalls, rapids, and top-notch swimming spots await in this densely forested corner of the Smokies.

This 19th-century building inadvertently preserved the handprints of its builders within its walls.