This medieval sanctuary's tree-framed door looks like a portal to a mythical realm.

England's most notorious suicide spot.

This domed temple was built in a hidden cave mouth as a refuge for sinners seeking absolution.

Europe's largest natural bridge has a 19th century royal chateau built into its side.

Fossils, railroads, and waterfalls!

Swarovski's museum/theme park is a fake diamond fantasia overlooked by a giant.

At high tide this strange footbridge appears to have no purpose whatsoever.

The factory for the popular Dumbo location, the Greenpoint shop is a quiet gem.

Obelisks and stone pineapples in the Irish countryside.

The ruins of the castle that chemicals built.

An abandoned theme park with a strange and tumultuous past.

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

Beyond the usual stories that attend old prisons, this one has deep bloody undercurrents.

This abandoned asylum in Wales might look haunted, but it's still beautiful.

Super-heavy Nazi architectural experiment.

A haunted hot springs hotel that went from healing retreat to asylum before it was restored.

Below a historic English market town lies a secret underground city complete with kitchens, laundries, storerooms, and an underground lake.

A labyrinth of ancient tunnels hidden below the city holds the ruins of 2,500 years of history.

This sacred cavern, 400 feet deep, is home to millions of bats and an ancient burial ground.

The remains of the iconic train crash from the movie The Fugitive can still be found rusting along the Great Smoky Railroad.

Over fifty whirling pools left by the glacial age.

David Sedaris called it "The greatest shop in the world."

Defying all odds, this lonely little tree found a home on a log sticking out of a Canadian lake.

Vortex-shaped aquarium hosts Europe's largest school of piranhas and other ocean creatures.