The only residents of this abandoned housing development full of identical castles are stray cats and dogs.

Mausoleum and Holy Seat of Antiochus I of Commagene.

A Turkish monastery tucked into a cliff wall.

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

An abused and forgotten metropolis, abandoned for centuries.

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

This hunter-gatherer architecture is believed to be the oldest religious complex known.

Get in line for Lisbon’s most famous sandwich.

An abandoned tuberculosis hospital said to be haunted by the patients who died within its walls.

The medieval castle built as headquarters for the Pope's secretive Knights Templar.

A unique seaside cave where Aleister Crowley faked his own death.

An ancient and majestic fortress that played an integral role in Portugal's road to independence.

Perhaps the most spectacular grotto along the Algarve coastline.

This unreal Portuguese palace looks as though it's made from a pile of different castles.

This eccentrically decorated palace is replete with grottoes, fountains, tunnels, and caves.

A maze of underground tunnels beneath one of the most beautiful forts in Serbia.

This memorial park stands on the site of one of the largest mass executions of the Second World War.

A sinuous path among steep cliffs creates a stunning sight in southwestern Serbia.

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

The convergence of two currents makes this a surprisingly pleasant getaway in the Arctic Circle.

A serpentine highway twists and turns over the treacherous Norwegian Sea.

Ruins of a former government building destroyed during the Georgian-Abkhaz war in the wake of the fall of the Soviet Union.

Fortified homes of highland warriors that are still in use today.

Luxury hotel turned into a refugee camp, then turned back into a luxury hotel.