A spectacular cave and a beguiling lake.

A small but immensely extravagant palace built by the "Night King."

The world's second-largest sundial, made entirely out of stone.

An isolated dive site teeming with cnidarians.

The world's second-largest excavated hole.

A self built castle built by a salt worker in Brazil.

The world's highest and most dangerous infinity pool lies at the precipice of Victoria Falls.

Fall down the rabbit hole into a surreal journey of human consciousness "from ass to soul."

World's largest permanent maze made of 18,000 conifers.

A beautiful maze marks where three countries meet.

A complex, nine-layer maze on the grounds of a Venetian doge's playground.

An Amazonian hotel is the ultimate treehouse and provides stilt based accommodation.

What is left of the pillar of Saint Simeon, the voluntary martyr who climbed the column to give his sermons, remaining perched there for thirty-seven years.

Come stay at a live-in art installation.

The intricate stonework of Machu Picchu serves as a testament to Incan engineers.

A tunnel once abandoned now thrives with graffiti art as an off-limits makeshift gallery.

Abandoned Nazi train station turned underground astroparticle laboratory.

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

A unique underground structure dating back to the 1st century BC.

Below a historic English market town lies a secret underground city complete with kitchens, laundries, storerooms, and an underground lake.

Earth's greatest purely vertical drop at 4,101 feet.

A massive forgotten storehouse from 1913 on the Brooklyn Waterfront has a spectacular view of Brooklyn.

Nazca pilgrimage site covering 370 acres is a popular stop for archeologists and looters.

The world's tallest church tower reveals a spectacular view to anyone up to the task of climbing the daunting staircase.