This strange bovine gargoyle is said to have been put in as a passive aggressive form of revenge.

This private skyway is filled with art and was expanded explicitly so that Hitler could appreciate a river.

A mysterious chasm in the heart of the ancient Roman Forum, the Lacus Curtius was once believed to be a gateway to hell.

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

A real flying saucer, contracted by the U.S. Air Force.

Ruins of a Carnegie family mansion on Cumberland Island.

A surviving remnant of the thick ice mass that once mantled most of Western Canada's mountains.

Fossils, railroads, and waterfalls!

Few other hotels can rival the grandeur of the Castle in the Rockies.

The only road through the heart of Glacier National Park.

An architect's childhood fantasy treehouse made real.

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.

The last physical evidence of the Lewis and Clark trail is one of their autographs etched into this giant rock.

The drama of nature in full effect in this Nevada State Park.

Giant, natural amphitheaters made of delicate geological formations called "hoodoos."

A dramatic, 360-degree recreation of Pickett's Charge in the Civil War.

A labor of love built by local hang-gliding enthusiasts, this ideal launch spot was outlawed by the authorities and has since been largely abandoned.

Bizarre Cavern.

European castle ruins in an American state park are actually the product of death and grief.

Labor provided by Great Depression-era programs restored these 25,000 acres in Tennessee.

All you ever needed or wanted to know about America's favorite whiskey, but not a drop to drink.

Moonbows over Kentucky.