A castle perched precariously over the Crimean Sea.

This precariously perched fortress was once ruled by a crow-worshipping baron.

A historic observatory precariously perched at the "Top of Europe."

An otherworldly restaurant perched on the edge of a jagged cliff next to a medieval holy city.

Ninety feet off the valley floor is an ancient dwelling put under protection of the U.S. government by Teddy Roosevelt.

A deserted hodgepodge of experimental structures designed by nearby university students.

A well-preserved network of cavernous tunnels have spent silent centuries removing Toronto's waste.

An old curiosity shop holds on to a centuries-old tradition of manually-distilled rose water.

Burbling away in refrigerators are 105 sourdough starters from around the world.

A collection of the specialized tools used to construct Japan’s beautiful architecture.

The largest cactus farm in Africa.

This giant Buddha statue has 125,000 smaller Buddhas hidden inside it.

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

During the holidays, a vintage subway train whisks New Yorkers back in time.

Bronzes and busts that once stood in the city's main squares are now relegated to a small hidden courtyard.

The crumbling structure is a rare surviving relic of the area's bygone mining industry.

A crumbling World War I fort that is reached through a series of concrete tunnels.

An abandoned film set location for a remote spaceport in a galaxy far, far away hides in the Tunisian desert.

Some believe this abandoned Brutalist masterpiece inspired George Lucas's Sandcrawler.

A statue of Vladimir Illyich Lenin guards this abandoned building in the "Forbidden City."

Sited in an Inner Mongolian desert are the remnants of an important trade stop along the Silk Road.

One of the last examples of Soviet architectural propaganda has a few technological tricks up its sleeve.

This abandoned Navy base was transformed into an off-grid alternative living community for thousands of people.

An off-grid art installation that encourages its visitors to imagine a world without waste.