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

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

2300-year-old Roman road connecting the empire.

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

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

The celebrated eyesore created by starry-eyed sweethearts.

A majestic lion statue guards this Parisian botanical garden, and feeds on an unsettling item.

A horde of stray cats rule in this secluded Parisian cemetery under a bridge.

Magical-looking cottages that inspired one of the most famous animated films ever.

Hollywood's most famous landmark, the "temporary" sign that has stood for decades longer than intended.

A massive Montreal stadium that has seen nothing but trouble since its inception.

A historic Montreal market that was the city's agricultural hub for over century.

Designed by Buckminster Fuller, this relic of the 67 Expo survived fire and ice.

This awkward aquarium sculpture is one of the strangest statues in Chicago.

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

The unluckiest U-boat in the entire German fleet is now on display in a Chicago museum.

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

Years of archaeology, just chillin' by the water cooler.

Four glass boxes hover over 1,000 feet in the air to give visitors an unparalleled view of Chicago.

This nearly 200-year-old restaurant's history includes an exiled French prince, JFK, and a very hungry Daniel Webster.

An interesting decoration on this historic site, this weathervane comes with as many legends as it does questions.

A former waterfront market is now in the center of town due to some interesting Boston engineering.

This landmark cemetery in Boston was created more than 300 years ago.

The site of Paul Revere's historic two lantern warning.