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

Hidden just under the waters around this Turkish island are the ruins of a once great city.

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

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

Where commuters walk through remnants of an ancient Greek necropolis.

This ancient Greek place of assembly and marketplace is being revealed layer by layer below the modern Athens cityscape.

Peace Park and the Atomic Bomb Dome.

A plaque marks the site directly below the mid-air detonation of the atomic bomb over Hiroshima.

A beautiful bamboo trail tucked in this famous Japanese Shrine.

Japanese national treasure originally built in 593 CE.

The sound of swaying stalks in this stunning grove has been named a governmentally recognized sound.

By day this New Orleans square is for pedestrians, but by night it is a kingdom of kittens.

This "second" cemetery represents New Orleans' attempt to keep cholera at bay.

In 2010, Nicolas Cage purchased two plots in this cemetery using one to construct this strange pyramid mausoleum.

A museum and shop on Bourbon Street located in the former home of the second Voodoo Queen of New Orleans.

The second oldest continuously operating bar in Louisiana.

This symbolic piece of New Orleans architecture is also home to a few ghastly stories.

The oldest cemetery in New Orleans, resting peacefully for over 200 years now.

The final resting place of New Orleans' most famous voodoo priestess.

The graveyard holding the remains of George Washington's slaves was forgotten for nearly 200 years.

This isn't your average roadway—it's actually a National Park and a transportation pioneer.

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

The semi-reclaimed ruins of this canal were once part of an ambitious plan to reroute the mighty potomac.

The last holdout of a pre-Civil War rebel who took the matter of slavery into his own hands.