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

Underground monastery and fortress.

Ancient rock-hewn town that witnessed key events of Georgian history.

The village's cobblestone streets are lined with shops displaying exquisite copper craftsmanship.

This mysterious but iconic tapered tower appears in many Azeri fairytales and legends.

The building's fluid, wavelike walls are a true feat of architectural ingenuity.

What might be the largest completely Jewish town in the world outside of Israel now faces dwindling numbers and empty streets.

Foreign invaders almost left this lovely Caucasus palace alone—almost.

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

Resonant stone, that has been played since prehistoric times.

Home to nearly a third of the world's mud volcanoes, Azerbaijan is home to a messy, bubbling, and sometimes explosive landscape.

Mysterious hillside with a continuously burning natural fire.

This ancient hydrological marvel is now the base of a modern outdoor cinema.

The ruins of an abandoned medieval city where the last Byzantine emperor was crowned.

These little castles each held thousands of pigeons.

One of the world's largest salt caves is filled with fragile salt sculptures, salt rivers, and huge salt megadomes.

Putrefaction plateaus in Iran, where the dead were sent for decontamination before going to their final resting place.

The palace of the King of Kings, burned by Alexander the Great.

Iran's colorful terraces are a rare geological masterpiece.

Mirrors and glass shards cover every inch of this arrestingly beautiful mosque.