One of the oldest student jails in Germany.

This German museum is devoted to all aspects of grave culture from headstones to coffins.

Strange physical sensations and optical contradictions keep visitors coming back for more.

Known by nicknames like the "Jersey Jumper" and the "Daring Yankee," Patch was the first famous daredevil in the United States.

A tiny, heartwarming piece of art hiding in plain sight.

The subterranean "lake" below the Paris opera house inspired the Phantom of the Opera's lair.

The medieval legend behind this holy well was one of the inspirations behind "Alice's Adventures in Wonderland."

This hidden 13th-century tavern room has a few Shakespearean connections.

The quarry was abandoned over 100 years ago, after a massive ammunition explosion ended in tragedy.

The wooden octagon in which Huckleberry Finn and A Connecticut Yankee were born can still be visited in upstate New York.

Abandoned for over a century, this chilling train tunnel is now a destination for ghost hunters.

Western New York's largest independent bookstore doubles as a historical repository of all things Niagara Falls.

The "last holdout of the Confederacy” actually sat at the edge of the Canadian border.

Mysterious stone faces line a hidden path great for seeing wildflowers, bird watching, and rock climbing.

This ancient burial site was once thought to be the home of a race distinctive to Ainu folklore.

A six-story treehouse offers spectacular views of New York's Finger Lakes region.

Near this allegedly haunted pub, you can find strong spirits on the rocks.

A kaleidoscopic warehouse-maze of handmade neon signs.

Tombstones and enigmatic inscriptions hide within a vault beneath a popular London arts venue.

It's a mystery why these remains were found with no traces of their bodies in sight.

The plunge pool is a surviving relic of a rowdy royal residence.

At this monastery, monks make raw-milk cheese and use excess whey to create methane that powers their hot-water system.

According to legend, this cavern holds the passage that Persephone used to travel to and from the underworld.

Once one of the largest rooms full of books in the world, this bookstore basement is still a treat for bibliophiles.