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

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.

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

From under the bed of one of the co-founders, this server helped launch the notorious file-sharing website.

At the center of an island in the middle of the Indian Ocean is a deep chasm ringed by tall waterfalls.

A Himalayan monastery claims to have a piece of a centuries-old abominable snowman.

The name of this tiny pocket park tucked between two buildings on Manhattan's Upper West Side is Latin for its location: "seventy-one."

Unusual hexagonal rocks formed by cooling lava named for their resemblance to traditional Japanese tatami mats.

A dilapidated psychiatric facility on the outskirts of Milan where electroconvulsive therapy was developed and Napoleon once lived.

A 19th-century subterranean reservoir repurposed as a contemporary art cave.

The unbelievably opulent home built for an infamous newspaperman.

This mysterious underground cave in Shropshire dates back to the 18th or 19th century.

The garage at the childhood home of Steve Jobs was a hangout for the founders of Apple, even if they never built computers there.

The painted and decorated towers of this Hindu shrine were once the tallest structures in one of the oldest cities in India.

An elegant chandelier hangs over this ancient sewer chamber, now open for concerts and public tours.

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

A Japanese concept restaurant that feels like a party thrown by the monsters in your closet.

Fonts are born and bred here at the oldest letterpress type foundry in the United States.

The cedar tree in Highgate Cemetery earned its title by accident.

The venerated body of a 12th century saint is celebrated each year with the 'Race of the Candles.'

This 700-year-old street food market features baby octopus and soy donuts.

This large midwestern cavern features impressive rock formations and an underground waterfall.

The "Seinfeld" diner.

The bones of some 7,000 soldiers killed in the historic Battle of Solferino are stored here.