The engineering wonder and pleasure dome of a much-maligned emperor still holds undiscovered secrets.

Affectionately known as "Lord Bot," this historic statue has a cult social media following and rightly claims to be “the most metal inhabitant of the Wren Yard.”

The romance of early commercial flight still fills this Art Deco destination.

The Kirkland Monument remembers a selfless Civil War hero who braved the battlefield to give water to his dying enemies.

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 remains of a historic plantation nestled in between a parking lot and the rental car return at Reagan National Airport.

Forget Hollywood, one of the biggest stars in the world can be found in Roanoke, Virginia.

This stately building in Alexandria, Virginia was built by Freemasons to honor one of their most famous members.

This war hero's old shop remembers the fine line between medicine and quackery during the Revolutionary War.

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

A sacred site for Native Americans surveyed by George Washington and owned by both King George III and Thomas Jefferson.

The remains of a failed attempt at medieval nerdery are hidden deep in the woods of Virginia.

The bears of Bern have been a city highlight for over 500 years.

Caves famous for the dragon-slaying saint who lived there.

A nearly 500-year-old sculpture depicts a man eating a sack of babies, and no one is sure why.

This historic covered bridge contains a series of macabre paintings that communicate one thing: everyone dies.

This memorial commemorating fallen Swiss Guards of the French Revolution has been called the saddest stone in the world.

The spot where the fascist dictator made some of his most famous speeches including declaring war on Britain and France.

A mysterious chasm in the heart of the ancient Roman Forum, the Lacus Curtius was once believed to be a gateway to hell.

The yawning maw of this pagan visage is said to bite off the hands of liars.

Rome's semi-secret peephole vista is also a former Crusader stronghold.

A master of trompe-l'oeil creates a stunning, tourist-fooling dome out of a flat ceiling.

An alchemist's "magic door" stands in the middle of a Roman park.