The gondolas let you glimpse a bird's-eye view of one of the world's highest capital cities.

The narrow passages will challenge even the bravest driver.

The abandoned village of Skarð aptly illustrates the idiom "Don't put all your eggs in one basket."

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

Also known as the Square Colosseum, this building is a prime example of fascist-era rationalist architecture.

Brass cobblestones mark the places where individual Holocaust victims were taken from their homes.

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

This hill made entirely of ancient Roman jars was simply a garbage dump to the people of the time.

Museum dedicated to literary greats of the Romantic Period is also the home in which Keats met his untimely end.

This ritzy Italian market is built around a statue of an unforgiven heretic who was burned for his belief in an endless universe.

The final resting place of the poets Shelley and Keats.

The only "Egyptian" pyramid in Europe and the legendary tomb of Remus.

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

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

The pile of books behind the dignified writer gave the statue a most undignified nickname.

Thousand-year-old Viking runes adorn an ancient Greek lion at the entrance to the Venetian Arsenal.

100 year tradition of fist fights, marked by marble footsteps.

Because sometimes the most efficient route from A to B isn't a straight line.

Mary Kelly was last seen here before she was murdered by Jack the Ripper.

This beautiful Brooklyn monument over a crypt memorializes a grim and largely unknown story from the American Revolution.

The last remaining example of the boatmen's perches that once dotted the south bank of the Thames.

The longest continuous underwater road in North America was built at the insistence of Franklin Roosevelt.