The old observatory in Copenhagen has a spiral corridor used as a racetrack.

Wedding chapel's mysterious spiral staircase said to be miraculously constructed.

The ruins of an ancient island city built atop a coral reef in the South Pacific are spectacular and strange enough to have inspired H.P. Lovecraft.

An eccentric garden of sculptures crafted in India decorate an Irish green space dedicated to Alan Turing.

Curious rock formations in a tiny Kansas state park.

Caves famous for the dragon-slaying saint who lived there.

This mill on Lake Erie appears to shrink as a viewer approaches thanks to an optical illusion.

The biggest and deepest Cold War bunker open to the public can be found in southeast England.

The granddaddy of all tourist traps, built on ice water, jackalopes, and a giant dinosaur.

Home to the "Circus" trees created by Axel Erlandson.

An old trolley bridge was converted into a breathtaking garden bursting with colorful flowers.

Centuries-old bridges grown from tangled roots.

These tracks are believed to be from a panicked dinosaur stampede.

Treehouse motel and treehouse-building school.

A gigantic 10-foot tall stone man.

Possibly the most beautiful carillon in the world, set atop Iron Mountain in Florida.

Occult books, tarot, oddities.

France's most famous cemetery, with some of its most curious tombs.

The Mysterious Witch Bonney, a haunted statue in an old industrial city.

These rows of World War II-era bunkers were the scene of some of the infamous Mothman sightings.

A toxic ghost town sitting atop a massive coal fire.

An experimental, automotive replica of Stonehenge.

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

A museum dedicated to the alleged Roswell Incident.