This harsh mountain path was built as a strange attempt to improve the health of Turkmen citizens.

This mountain trail inspired Nietzsche to complete his magnum opus.

The longest manmade tunnel in Queensland is now a beautiful trail, home to a special colony of bent-wing bats.

These quintessentially English stepping stones were built for Victorian tourists.

The home of Ireland's last leprechauns is officially protected by the European Union.

This trail leads to a mine that was used as a sanctuary during the Great Fire of 1910.

Historic, 19th-century wagon wheel ruts cut into soft volcanic ash.

A serene desert oasis speckled with ancient artifacts.

A remarkable lava formation encloses a line of Buddhist statues that can't be accurately counted, according to local mythology.

An unassuming secret door once led to a legendary watering hole.

Dance on a hand-hewn log floor padded with bouncy boxcar springs at a saloon built in 1883.

A rooftop restaurant hides in plain sight atop Vienna's Palace of Justice.

A treasure trove of artifacts, books, and artwork from the "golden age" of exploration.

A grove of "candelabra redwoods" deep in California's Lost Coast.

This jaw-dropping 19th-century bridge uses its reflection to form what appears to be a perfect circle.

A taste of Middle Earth, in the middle of the Bayou City.

Designed as a labyrinth, this subterranean prison was crafted without bars or doors.

This grove of ghostly cedars was killed in 1700 by an enormous tsunami, felt from the United States to Japan.

One of the largest, oldest, darkest, quietest motel rooms in the world.

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

In a 345-million-year-old cave that's 200 feet underground, dinner awaits.

Six tiny houses built for working class people form the largest intentional cluster of Wright homes anywhere.

The oldest stone house in Paris was built by its most famous alchemist.

The United States's largest hand-dug well is topped with a state-of-the-art museum.