Old Danish castle immortalized in Shakespeare's Hamlet.

Four cars from the old system were once on display, but were removed in 2014.

The remains of a 19th century spring, and the site of an infamous unsolved murder.

This rocky spread has been squeezed up directly from the bowels of the earth.

This cave holds a surprisingly colorful variety of geological oddities.

Antarctica's bustling metropolis, originally established by Richard E. Byrd.

Fire meets ice at the southernmost volcano on Earth.

Massive volcano in the Andes is the farthest point from earth's center.

A world-class collection of mechanical musical instruments and automata.

This massive boulder is either a unique rock formation created by glacial melt or a magic energy vortex.

A 1950s eccentric's vision of Eden preserved as a hiking trail.

Anatomical cabinet holds unexpected treasures.

Sacred waters rescued from the wrath of a volcano.

A Japanese pilot crash-landed on this Hawaiian island after the Pearl Harbor attack and terrorized locals for a week.

A newspaper editor turned this abandoned island into a tortoise nature preserve that's now the world's smallest national park.

An abandoned set from the 1980 film "Popeye," claimed and repurposed as a theme park by creative locals.

Once home to over 8,000 exiled Hawaiians suffering from Hansen's Disease.

Extensive Orthodox icon collection in Andorra.

Doris Duke's lasting collection of Islamic Art, hidden in a Hawaiian paradise.

A Hawaiian stairway to heaven—that you can't climb.

An ancient Ethiopian cave church is endangered by the simple building of a road.

Aqua white sand highlighted with fiery red rocks.

One devoted couple has donated multiple recreations of Michelangelo's sculptures to this South Dakota town.

The Origin of On the Origin of Species.