This was once the largest city in Kazakhstan, and a major stop on the Silk Road.

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

This mysterious cliffside carving of an ancient Hittite deity has baffled scholars for centuries.

A mountain pass in Bulgaria's Balkan Mountains was the site of four historic battles.

An abandoned saucer-shaped monument in the Bulgarian mountains.

A magnificent, glittering building tucked into a tiny Bulgarian mountain town.

An architectural marvel that spans the Arda River, and has stories of a haunted past.

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

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

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

This 14th century castle withstood years of battle but is now sliding off the hills into the Danube.

This fairy-tale castle would make Dracula (who is said to have been imprisoned there) jealous.

This 11th-century structure is one of the oldest churches in Romania.

The possible imprisonment of Vlad the Impaler here earned the medieval castle its nickname, "Dracula's Castle."

A medieval church built up to defend its village.

Packed to the ceiling with antique taxidermy and hunting arms.

Climbing to the top of the cathedral's bell tower offers sweeping views of these medieval ruins.

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

A Romanian church built from one single oak.

These ancient pecked images are among the oldest and best-preserved in Mongolia.

Unusual, mushroom-like rock formations caused by weathering and water erosion, set to disappear, according to geologists.

The site of the little-known Pennsylvania battle that sparked the Seven Years' War.

Pennsylvania's highest point is spotted with boulders which were pushed to the surface by nothing but cold.

This massive sycamore tree has been labeled as one of the largest in the state.