The deepest underground city in Turkey was designed to protect 20,000 people behind massive stone doors.

These ancient sunken lanes were naturally tunneled into the soft ground by countless footsteps.

This historic stone bridge has an entire neighborhood clinging to its sides.

A town church once nearly submerged by the damming of a river is now hauntingly visible as the water recedes.

Rome's semi-secret peephole vista is also a former Crusader stronghold.

An abandoned set from the 1980 film "Popeye," claimed and repurposed as a theme park by creative locals.

This giant boulder is pinched over a 1000-meter abyss by two mountains.

In this historic region, homes and churches are carved into ancient volcanic rock formations.

An unfinished tomb carved into a giant boulder in the Arabian Desert.

Started nearly 100 years ago, this science experiment just keeps on going, ever so slowly.

Bowl in splendor, if you're lucky.

Perched on a spindly rock spire in a Greek archipelago, this lighthouse would make a perfect wizard's tower.

Stunning examples of Russia's 18th-century wooden architecture.

An abused and forgotten metropolis, abandoned for centuries.

A salty red wasteland in Tanzania is a breeding spot for endangered flamingos.

The hottest place on the planet.

On the outskirts of a desert trading village high on the Andean plain, steel giants have been destroyed by salt winds.

A canvas of crops grow from vibrant red soil in this terraced farmland.

There is only one place in the world where the corners of four nations come together.

The entire length of the border is marked by a 20-foot-wide slash through the trees.

The only runway directly into the magic kingdom has been closed since 1972, but it still sings to you if you drive fast enough.

A natural gas leak provides a flickering flame beneath a waterfall.

Flames have been burning within this mountain for more than 2,500 years.

A shrine of fire worship built on top of a natural flame.