A marvel of Byzantine engineering under the streets of Istanbul.

A mysterious ancient cemetery with Roman sarcophagi and Lycian inscriptions.

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.

The ancient latrines of the Greeks, in all their public glory.

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

An organ located deep within a cave, whose "pipes" are the geological features of the cave itself.

A sprawling collection of over 106,000 toys from around the world.

A unique geological area spiked with wind-carved rocks that resemble teepees.

A phenomenal assembly of pueblos in New Mexico is the most complete example of ancient ruins north of the border.

The world's largest military aircraft cemetery.

See massive fossils that are over 200 million years old in northeastern Arizona.

This 4,000-foot-diameter hole is touted as "the most well known, best preserved meteorite crater on Earth."

The quintessential Japanese rock garden has existed for more than 500 years.

This spa theme park lets its guests take a dip in pools of coffee, wine, or ramen broth.

A bronze statue dating back as far as 1252, still has remnants of gold on its right cheek from ancient gilding.

After a profound show of devotion for his master, a dog becomes the symbol of loyalty for an entire nation.

Metro station with a claim to rock n' roll fame.

On the Spree bank, discover one of the last reminders of a symbolic wall that divided, and was torn down by the people.

Cold war icon and onetime "hole" in the iron curtain.

The most visited, and possibly most controversial, museum in Germany.

At 207 feet, one of the world's longest continuous escalators.

A former major munitions plant that has been converted into a sprawling art space.

Light bulbs, scrap wood, and tinfoil comprise this homemade throne of the gods.

A museum dedicated to exhibiting remarkable outsider art.