The hollow trunk of this 650-year-old tree was used as a hideout by two Jewish brothers during World War II.

The largest retailer of seashells in the world.

A perilous medieval road leading right into the sea.

An institution dedicated to curiosity, logic, riddles, and Mongolia's long history of puzzles.

About 80% of all U.S. avocados are descendants of Rudolph Hass's glorious tree.

What might look like a cliffside sacrificial altar at first glance is actually a stone compass pointing to cities and lighthouses all around the world.

This network of tunnels housed an entire village for years, and even had a hall for screening movies.

This poor little statue is the most vandalized memorial in Washington.

The giant Siberian crater known locally as the "doorway to the underworld" is expanding every year.

Small teepee-like houses built for TB patients have become sheds, studios, and bus stops around Colorado Springs.

This graceful little figure is a one-of-a-kind version of the cherished character.

This art center is way beyond your average pumpkin-carving operation.

The Arctic Circle runs through this isolated spot north of Iceland.

Trace the history of writing at this unusual North Carolina destination.

The unbelievably opulent home built for an infamous newspaperman.

An absolutely beautiful 200-foot stained glass installation traces the evolution of knowledge.

Members of Congress have traveled between the buildings on Capitol Hill for a century hidden from tourists, press, and storm clouds.

According to a satirical conspiracy theory that persists today, this German city of 300,000 is a hoax invented by the CIA.

One family's mission to exemplify sustainability took on a whole new life as a surprisingly beautiful home.

Modern design and unusual architecture make this mountaintop temple no ordinary Buddhist retreat.

A mistaken marker makes an erroneous claim along the historic Old Divide Road.

A local dialect born in the late 19th century is only spoken in this isolated California valley.

Iceland's largest geothermal mud pool is a little bit haunted and a little bit dangerous.

A climbing route in the mountains of Italy’s Dolomites, built for soldiers during World War I.