Founded in 670, this ancient mosque is an architectural time portal.

This 6th-century church has the largest and best-preserved collection of Byzantine mosaics outside Constantinople.

An incredible mosaic-lined monument said to have held the remains of an ancient Roman empress.

What appears to be an ancient Roman temple is actually a Catholic church.

Inside this building is another country within Rome, a sovereign entity without a physical territory.

Breathtaking and huge 430 year old maps of Italy.

Historic fortifications form the boundary of Vatican City, but it’s not entirely surrounded by walls.

The floor of this spectacular Baroque sanctuary is covered in memento mori.

This spectacular dome managed to survive after being bombed in World War II, in an event known as the "Miracle of Mosta."

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

This remarkably well-preserved Egyptian plinth is pretty well traveled for a giant piece of stone.

A fountain standing as a testament to a doomed alliance.

A marvel of Byzantine engineering under the streets of Istanbul.

Five sultans and their families rest in eternal splendor, teeming with overlooked beauty and drama.

A section of the long chain that blocked enemy ships from entering Constantinople.

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

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

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

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

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

Balanced on four stone pillars, this historic tower was the site of a tragic political assassination.

A museum glorifying the life of Stalin, located in the city of his birth.

Ancient rock-hewn town that witnessed key events of Georgian history.

A small but hugely whimsical theater where marionettes play out the "The Battle of Stalingrad."