Abandoned railway line circling the city of Paris.

The vast, legendary catacombs hold secrets much stranger than stacked bones.

Named for the 39 tribes that live in Oklahoma, this restaurant's menu deliciously highlights local flavors.

Claims to be the "World's Highest Hill."

A larger-than-life monument to the overlooked women who braved Western expansion and broke down societal barriers.

The highest point in Oklahoma used to be a lawless outlaw's paradise.

A natural rock formation believed to be a cure-all.

Over 50 historic windmills whir away at this outdoor museum.

A detached cement mixer has been transformed to resemble a relic from some obscure NASA mission to Oklahoma.

An old spiral fire escape dangles above a public courtyard in Midtown Oklahoma City.

Only museum dedicated to women pilots, with personal artifacts from Amelia Earhart and other aviatrixes.

When you can afford only half a road, you build only half a road.

A peculiar forest that was handcrafted for government experiments.

American bison herd descending directly from a Bronx Zoo breeding program that saved the species from extinction.

A former chicken restaurant that doubled as a speakeasy is now a quirky home full of wonderfully strange traditions.

This historic folk art garden contains a nightmare tower that claims to be the world's largest concrete totem pole.

Travel through the hidden underbelly of the city in colorful tunnels filled with art and history exhibits.

An immersive art experience built by local arts collaborative, Factory Obscura, in the building formerly known as The Womb, a psychedelic arts center founded by the frontman of the Flaming Lips.

An acoustic anomaly with a mysterious cause.

This Luxembourg cave is covered in cryptic looking marks left by mining activity.

An expansive complex of subterranean tunnels is all that remains of one of Europe's most formidable medieval fortresses.

This noble mash-up in eastern Luxembourg is part Medieval, part Renaissance, all castle.

This tri-part waterfall is a little bit of fairytale beauty in the heart of Luxembourg's Little Switzerland.

The last bastion of Roman presence north of the Alps looms over a German town.