Underground monastery and fortress.

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

Submerged busts of communist and socialist figures from the USSR.

Submerged trees jut ghost-like out of an idyllic turquoise mountain lake.

Glacial lake that mysteriously empties itself every year.

Extremely isolated Silk Road caravanserai in the middle of nowhere.

Final palace complex of the last of 29 Kokand rulers.

Light still pours into the ruins of this ancient Islamic observatory.

The Avenue of Mausolea is a series of grand palatial tombs.

The largest dam in the world and the site of a potential disaster.

Tibetan-influenced mountain fortress in Northern Pakistan.

Known as the most dangerous bridge in the world, the Hussaini Hanging Bridge is only one of many precarious rope bridges in Northern Pakistan.

The place that allegedly inspired James Hilton's depiction of Shangri-La.

The world's second largest salt mine, said to have been discovered by Alexander the Great's horse.

What was once supposed to be the symbol of a shining Afghan future is now a bombed-out ruin.

Celebrated as a center of civilization, the remains of the ancient city have been nearly destroyed by greed, egoism, and war.

More than 100 monumental tombs carved into rock are preserved at this ancient Nabataean site in the Arabian Desert.

A giant portrait of an ancient king looms over the river.

Bizarrely shaped rock formations in northwest Bulgaria come with equally bizarre legends.

Step back in time and witness the fall of Constantinople.

The rocky remains of an ancient Greek forest.

The hermits of Karoulia protect their asocial lifestyles by living on the vertical face of a treacherous precipice.

This famous city eluded concrete detection until the early 2000's.

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