The footprint of a frustrated devil in Munich's Cathedral.

The prototype for all Nazi concentration camps.

An earthwork sculpture built by Robert Smithson in the Great Salt Lake only reemerges during drought.

Castle and secret tunnel withstood a siege until its owner was killed by the Holy Roman Empire, while sitting on the toilet.

A lovers' beach, tucked below the surface of the island, provides a safe haven for romance.

The headquarters of the Mahanikai school of Buddhism, Thailand's largest monastic order.

Step inside Lucy, the world's largest "elephant."

A gargantuan crystal kingdom.

Tiny Swedish village with a distinct local phenomenon known as an "Elk Shower."

A Swedenborgian glass church surrounded by redwoods sits perched atop a massive landslide area.

Sloth rehabilitation center in the jungle of Costa Rica.

A house carved into a rock in the 1940s.

One of the oldest living oak trees in the Southeast.

Exotic feline breeding compound and conservation center.

The famous author's cottage hideaway.

Prove you deserve to be fed by Kenny Shopsin.

The hidden "ballroom" under a mansion lake was built by a criminal who ate a cyanide pill during his trial.