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

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

This solitary monastery may hold the remains of Vlad the Impaler (but probably not).

An abandoned saucer-shaped monument in the Bulgarian mountains.

This massive concrete sculpture is said to be the heaviest communist monument on Earth.

Roman ruins, natural methane fires and a lovely beach.

Once described as the "Eagle's Nest," this ruined ancient city rests on a remote mountaintop.

A marvel of Byzantine engineering under the streets of Istanbul.

Roman ruins top white travertine terraces formed by ancient hot springs.

Fantastic lake on the heart of a fault line.

Naturally protected city carved from a rock face.

In this historic region, homes and churches are carved into ancient volcanic rock formations.

Live a night as a Byzantine King, with a minibar and private jacuzzi.

A gleaming white and undulating tower marks the border between Georgia and Turkey.

A sacred lake with thousands of sacred carp and a biblical history.

An ancient church on a tiny island covered in stone bible stories has controversially been turned into a museum.

Named after a legendary garden called Eram in southern Arabia, built by order of Shaddad, an Arab king who wanted to compete with Paradise.

Whitewashed mosque contains the world's largest carpet.

This bazaar is one of the oldest in the Arabian world.

The most alien-looking place on Earth.

Over two-thirds of the world's population of giant tortoises live among this coral formation.

Fabulous formations, weird and wonderful wildlife.

The centuries-old trees lining both sides of this dirt road may become Madagascar's first natural monument.

Only two of these trees remain in the natural world, found high in the cloud forest of the island of Mauritius.