The "Greatest Sewer" of ancient Rome is one of the oldest sewer systems in the world, and is still in use.

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

2300-year-old Roman road connecting the empire.

A detailed pachyderm supports Rome's smallest Egyptian obelisk.

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

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

Hundreds of lucky felines haunt the ruins where Caesar was murdered.

The crypts of Capuchin friars decorated with the bones of over 4,000 friars, including an entire "crypt of pelvises."

This Boeing KC-97 tanker is now a restaurant for aviation lovers.

The spot in the Mile-High City that's exactly 5,280 feet above sea level (at least for now).

A small horde of mythical creatures lurk almost imperceptibly within the museum's wildlife dioramas.

An annual festival celebrating Colorado's most famous frozen corpse.

Once a mortuary that held the remains of Buffalo Bill, this Denver hotspot is now a death-fixated restaurant.

The American Revolution was galvanized into serious action due to the tragic clash with British soldiers that occurred at this location.

A prehistoric rock shelter that's literally in someone's backyard.

In the middle of a suburban Denver neighborhood is a cave that once provided solace for a prominent Ute chief and his family.

The most photographed house in Maine looks good enough to eat.

When the town wouldn't allow the fast-food behemoth to build a new restaurant, they put one inside an 1850 home.

Explore some of the most unique vehicles in history along with a cast of unsettling mannequins.

To find the "unicorns of the deep" you've got to go downstairs.

This memorial plaque remembers a strangely shallow maritime disaster known as "Chicago's Titanic."

At Chicago's revered Field Museum, visitors are invited to learn about and literally explore DNA.

Wall to wall taxidermy at Denver's oldest and most exotic steakhouse.

Legend tells how a Spanish soldier disappeared from this isolated sentry box without a trace.