The seamy, underground secrets of Portland's criminal past.

The unique waterfall in Iceland's south features a backdrop of geometric black lava columns.

This 1,300 year old monastery built atop a single rock was once only accessible depending on the whims of the tide.

The world’s oldest and biggest bookstore stocking only mystery, crime fiction, espionage, and thrillers.

A miniature rainforest is growing inside of a Midtown Manhattan office building.

This futuristic German spa allows visitors to float in a pool of salt water while zoning out to underwater techno.

Hot springs monkey spa in the middle of Hell's Valley.

Medicinal spa created with the discharge from a geothermal energy plant.

The fairy tale castle of the "fairy-tale king."

For two weeks every June, fireflies in the Smoky Mountains perform an astonishing light show.

The oldest family-run luncheonette in New York, last renovated in 1948, still serves food and drinks the old-fashioned way.

Try not to get slimed in Tribeca.

A whimsical and twisted animatronic monster tour beneath the streets of Berlin.

A tour of underground Berlin takes you through WWII air raid shelters and tunnels used to smuggle people out of East Germany.

This dramatic landscape hidden on the Isle of Skye looks as though you've stepped into the magical realm.

High on a hill overlooking Los Angeles lives a world famous, high power conical Tesla Coil.

This churchyard arbor is surrounded by hundreds of gravestones placed there by author Thomas Hardy.

This abandoned subway station beneath the Waldorf-Astoria hotel is allegedly used to secretly transport presidents.

A theme park that suffered massive flooding during Katrina was abandoned, and now proves irresistible to trespassing explorers.

A 140-year-old castle with underground caves hidden in San Francisco.

Dodge prohibitionists and slide through the telephone booth in Crif Dogs.

These fantastically named natural pools look like something out of a Scottish myth.

This beautiful building in the heart of Manhattan's Financial District was empty for decades.

Tucked in the back of this amazing antique store is an important piece of medical history.