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

Monasteries on rock pillars, once accessible only by frayed ropes.

This tiny Bulgarian town offers a stunning location in the mountains and a storied history.

An autonomous republic of Orthodox monks.

Ruins of the Crusaders' headquarters.

Naturally protected city carved from a rock face.

This ancient village and its adjoining cemetery have a beautiful history of death and remembrance.

This Armenian monastery was carved out of cliffs and named after the spear used to stab Jesus.

An abused and forgotten metropolis, abandoned for centuries.

The largest stone moai on Rapa Nui.

A Turkish monastery tucked into a cliff wall.

A harrowing trail up a mile-high mountain.

A fifth-century temple improbably built into the side of a cliff.

Huge concrete structures designed as an early warning system for Britain to detect enemy aircraft.

A unique underground structure dating back to the 1st century BC.

Series of underground houses inhabited continuously for centuries.

The world's first and only natural nuclear reactor.

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

World's oldest and largest space launch facility, once a secret missile testing site.

200-foot-high minaret and only remnant of Afghanistan's lost city of the Turquoise Mountain.

Rusting ships sit in a desert where a sea used to be.

Where Stoddart and Connolly suffered in the infamous Bug Pit.

A fiery crater has been burning in the Karakum Desert since 1971.

A chapel on a volcanic core, marking the end of a successful journey.