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.

This half-forgotten fortress was constructed by the Ottoman conqueror of Constantinople.

Roman ruins, natural methane fires and a lovely beach.

Climb a steep hill in 90 seconds on the second-oldest urban subway in the world.

This crucial gathering spot along the "hippie trail" still displays old notes between traveling beatniks and backpackers.

While not Turkey's deepest underground city, this subterranean redoubt is the largest.

The best-preserved ancient theater in the world.

Ottoman-era houses lovingly preserved.

The most metal church of all time was built in record time because of an international, pious pissing contest.

This Turkish cave boasts some rather bizarre associations with the King of Mount Olympus.

An Art Nouveau gem hides beneath the layers of city grime obscuring this once-magnificent building.

Flames have been burning within this mountain for more than 2,500 years.

Naturally protected city carved from a rock face.

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

The deepest underground city in Turkey was designed to protect 20,000 people behind massive stone doors.

A Turkish ghost town abandoned in a population exchange with Greece.

These tombs were built into the side of a mountain so that ancient angels could reach the dead.

A Lycian city of the dead carved into the hillside of Southern Turkey, complete with startlingly human touches.

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

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

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

An early masterpiece of Le Corbusier, a famed Modernist architect, hiding in plain sight.

This ferry carries passengers across the Rhine propelled by no engine or paddles but by the river's current.