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

In Texas, a replica Irish castle is home to a charismatic pack of llamas.

An annual celebration of the region's successful elk reintroduction program.

This sacred, circular cave is lined with pools so clear and still that it's hard to tell where the water begins.

On this romantic tidal island reachable only at low tide the tomb of a famous French writer overlooks the sea.

One of the world's tallest waterfalls wasn't revealed to the world at large until 2006.

This stunning limestone waterfall is the highest in Estonia.

A small metropolis of Pueblo cave dwellings have been carved right into the hillside of this national monument.

Once a dining hall for boarding school students, this lodge was a popular haunt for nuclear physicists working on the Manhattan Project.

The 7,000-year-old calcium carbonate formation creates a magnificent natural bridge.

This once-popular otherworldly landscape was formed by one of the largest volcanic eruptions in history.

This National Natural Landmark is one of the best examples of a “mass wasting” in the world.

Board a mine car and descend the #190 slope 300 feet underground into the Clark Vein of coal.

Buildings that dynamite couldn't bring down were abandoned because of bathroom issues.

It would take 35 firetrucks to fill this enormous glacial pothole.

The crumbling structure is a rare surviving relic of the area's bygone mining industry.

The 19th-century ruins hide deep in an overgrown forest.

The graffitied ruins stand hidden within the Pennsylvania woods.

One day a year it is legal to jump off of this astoundingly tall bridge that spans an Appalachian gorge.

The isolated final resting place for perished coal miners.

Hikers can still stroll beneath the long conveyer of this abandoned mining facility hidden in a West Virginia river gorge.

The only geyser in the state of Pennsylvania is caused by pressure from an abandoned coal mine outside of the ghost town Centralia.

Visitors to Salt Springs State Park are encouraged to literally put their two cents in Penny Rock.

Once the largest town in eastern Yuba County now sits abandoned.