Yugoslavia's biggest underground airport lies in ruins.

Said to be the only museum in the world dedicated to the most classic of all blooms, the rose.

The second-largest Jewish temple in Bulgaria was deserted after World War II, seized by the communist government and then abandoned again.

UNESCO-protected ancient burial ground.

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

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

The ceiling of Prohodna Cave in northern Bulgaria affords a peek at the sky via two deity-sized-eye-shaped holes.

This historic black and white monastery is one of Bulgaria's architectural jewels.

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

Nine centuries-old fortresses guard the walls of this medieval Romanian city.

Known as the Hintz House, this medieval pharmacy has been an apothecary's haven for nearly 450 years.

This snug medieval lane is one of the narrowest streets in the world.

Even drowned in an ocean of toxic waste, the remnants of this Romanian village stand tall.

A muddy alien landscape that is home to rare species of exotic plants.

The preserved arm of a third-century sorcerer is believed to have the power to lift curses and spells.

One of the oldest churches in Romania is believed to have been built on the site of a pagan temple.

Some call this eerie forest of crooked trees the "Bermuda Triangle of Romania."

This once-derelict building is now one of the most beautiful bookstores in the world.

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

This elaborately decorated, fairytale-like Romanian royal palace is one of the most striking castles in Europe.

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

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

A curious cave church carved into the face of a cliff.

This enormous abandoned prison was once dubbed the "Bastille of Romania."