Rock-hewn monastery complex with hundreds of cave structures tucked away into the mountainside.

These Stalin-era industrial 'death traps' hang lifeless above the city

Take respite inside this jaw-dropping church while climbing the volcano where Georgia's Prometheus was once chained.

Underground monastery and fortress.

A forgotten graveyard lost in the tangles of an overgrown garden.

This quaint Hungarian railway system is operated exclusively by children between the ages of 10 and 14.

A 19th century artistocrat's mansion, turned into a library, hidden in a modern library.

The maze-like transportation hub contains abandoned areas, derelict stores, and a resident bat colony.

This overgrown mountain village has been abandoned for nearly a century.

Stone pillars and a petrified wedding party in the hills of North Macedonia.

This 3,800-year-old site contains markers used to study the movement of the sun and moon and create a lunar calendar.

An abandoned resort in North Macedonia is a relic from the Communist Party of Yugoslavia.

Legacy of the earthquake that nearly wiped Lisbon off the face of the Earth.

A king's pet, a pope's gift, an artist's inspiration, and a tragic shipwreck.

This Industrial Age architectural and engineering gem helps visitors and residents alike traverse Lisbon, “The City of Seven Hills.”

Thousands of exquisitely carved stone water storage wells, hundreds of stone steps fill this exquisite medieval stepwell.

This fairy-tale, neo-Gothic church in the Azores is a world of magical realism.

A perfectly circular lake is formed by the crater of an ancient underwater volcano.

This abandoned five-star hotel is now a five-star urban exploration destination.

The highest peak in all of England is plagued by dangerously fickle climate shifts.

This aging storage facility is the world's largest brick warehouse.

This disused Cold War bunker has been restored to all of its early 60s glory.

A magnificent winding road through a steep valley, with deep natural caverns at the bottom

This Gothic Revival castle used as a shooting location for "The Secret Garden" and other films.