What is left of the pillar of Saint Simeon, the voluntary martyr who climbed the column to give his sermons, remaining perched there for thirty-seven years.

An abandoned saucer-shaped monument in the Bulgarian mountains.

Moss and stone turn this waterfall into an otherworldly liquid veil.

Hideout of thieves, monks, and goat-footed gods.

Hidden in a secluded Greek cove is a pristine beach marred only by the rusting smuggler's hulk stranded on its shores.

A spectacular cave and a beguiling lake.

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

A spectacular Bulgarian cave resembling a devil's head with a waterfall rushing down its throat.

An ancient Thracian city where fire rituals were practiced on the largest cult altar in Southeast Europe.

Once an opulent Art Nouveau hotspot, the Constanța Casino is one of Romania's most beautiful abandoned buildings.

Rock carving created 1,300 years ago 75 feet off the ground.

A Roman monument to their own civil engineering prowess.

The legendary cliffside castle of three-time Voivode of Wallachia, Vlad the Impaler.

Groups of prehistoric tombs that dot the mountains of northern Oman.

Over the dunes of the Empty Quarter, the mysterious music of the desert.

A gargantuan crystal kingdom.

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

A natural arch carved by a river gave its name to the so-called "Cave of Forgotten Dreams."

Mysterious lost empire of the Silk Road.

For more than 40 years this Barnum-inspired half-fox, half-woman has been telling fortunes from her cage in a Pakistani zoo.

A complex of six forts embedded in the Rajasthan hills.

A part of the world's largest marsh seems to be growing bright red Martian grass.

Named after the Goddess of Harvests, Annapurna is the deadliest member of the Eight-thousanders club.

This complex of vertically-excavated Buddhist, Jain, and Hindu monolithic temples in India's Maharashtra providence illustrates a spirit of tolerance characteristic of ancient India.