The site of the first battle of World War II.

The former Nazi concentration camp stands as a museum to remember this dark chapter in European history.

An underground city of salt.

Countless stories attempt to explain Poland's mysterious J-shaped trees.

The walls and ceiling of this Polish church are decorated with thousands of skulls, with another 21,000 skeletons just below.

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

A marvel of Byzantine engineering under the streets of Istanbul.

A little-known caravanserai hidden among farmhouses in the Turkish countryside.

This arch granting triumphal entrance into Antalya was designed to honor the emperor's visit.

A tiny park in the middle of some big power politics.

One of the most exquisite Lycian hilltop citadels in Turkey.

According to local legends, the shallow sandbar that allows visitors to walk across Orhaniye Bay has a tragic backstory.

This ancient city - home to nine civilizations - is soon to be buried under 200 feet of water.

A sixth-century Byzantine cistern hidden below a modern carpet store.

Ancient serpentine sacrifice holder that has stood the test of time.

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

The alleged house of the Virgin Mary is tucked away in a park and nature preserve on Mt. Koressos in Turkey and is holy to both Catholics and Muslims alike.

Legend says if you stick your thumb in the hole and it gets wet your wish will be granted.

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

1513 Turkish world map, full of European state secrets and snarky commentary.

A small etching on the white marble parapet was written in runic script by a Viking mercenary.

Ottoman-era houses lovingly preserved.

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

Naturally protected city carved from a rock face.