In the early Roman Empire, people deemed traitors and criminals were tossed to their deaths from this rock.

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

Charles Dickens was not a fan of the ghastly wall dressings in this 6th century church.

The ruins of the largest gladiatorial school in Rome are largely hidden under modern streets.

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

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

This Roman arch marks the location of an ancient gate at one of the Seven Hills of Rome.

The Vatican's secret porn-festooned bathroom was painted in erotic murals by one of the greatest artists of the Renaissance.

The Pope’s secret escape route.

This hidden alley near the location of Rome's first theater was the site of a curious miracle.

A building so large that it has its own weather.

Maryland's first (and last standing) toll house on America's first federal road established the state as the "Gateway to the West."

An industrial waste tourist attraction.

A local prank turned town icon.

Sail through this subterranean show cave that is home to a legend that would go on to name nearly everything around it.

When the Austin Dam failed it destroyed much of Austin...and then it failed again.

A retired firefighter created this contraption so he and his family wouldn't die if accidentally buried alive.

Curtiss is a forgotten figure in the early history of flight.

This lush forest valley was once mined for lumber to the extent that it was once nicknamed "The Pennsylvania Desert."

"Dark Sky Park" is heaven on Earth for astronomers, one of the rare U.S. locations with no artificial light pollution.

Contrary to what one might expect, ice forms inside this small cavern during the summer and melts during the winter.

Once the "Eighth Wonder of the World," this iron railroad bridge was decimated by a tornado.

This collection honors the iconic, and proudly American lighter that just won't quit.

A medieval setting reimagined into a unique art alley.