A nearly unconquerable island-fort in the Indian Ocean.

The walls of America's oldest masonry fort famously "swallowed" cannonballs.

The world’s highest ski resort was deserted after an 18,000-year-old glacier melted away.

This chimerical bridge/tunnel appears to dead end right into the sea.

Two towns are linked by an engineering marvel masquerading as a boring suspension bridge.

One of the most spectacular bridges in Spain spans a narrow chasm that divides the city of Ronda.

An abandoned railroad tunnel is now filled with bioluminescent bugs.

Building owners can take out tiles for free at this repository for historic building materials.

Step into a cartoon at this Seoul café that aims to evoke a two-dimensional scene.

George Martin's Caribbean recording studio now rots within the shadow of an active volcano.

The world's largest wooden structure.

The last occupied troglodyte dwellings in England weren't abandoned until the 1960s.

An ancient fortified mound raised over the millennia from settlements built one on top of the other.

A landmark in the history of technology and computing is hidden in a tiny Baroque chapel.

A crumbling mountain resort that looks like it was abandoned in an instant.

Six tiny houses built for working class people form the largest intentional cluster of Wright homes anywhere.

The world-record holder for the longest bridge stretching continuously over water.

The 3,600-year-old archeological sensation is considered to be the oldest representation of the cosmos.

The old Route 66 town straddling Texas and New Mexico died along with the Main Street of America.

The land is full of geologic eye candy, such as otherworldly spires, mushroom-shaped hoodoos, and prehistoric fossils.

A striking depiction of Teotihuacan's mysterious "Spider Woman."

Beneath a Virginia City bar is the entrance to an abandoned gold mine.

This cave system allegedly holds the "metallic library" of a lost ancient civilization.

This abandoned mansion has a window for every day of the year, and is a temple for ghost hunters.