The world's most active stratovolcano is almost always erupting.

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

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

The fishing boats that moor in this small lagoon enter and leave through a tunnel to the sea.

An abandoned set from the 1980 film "Popeye," claimed and repurposed as a theme park by creative locals.

An opulent monument built for a duke who donated his entire fortune to the city of Geneva.

The Swiss artist's bulbous and overgrown shape-shifting sculpture controversially graces the center of Bern.

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.

A historic observatory precariously perched at the "Top of Europe."

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

A mechanized clock where a man fights off a dragon, crab, and rooster.

If you look closely at the oldest bridge in Paris, you might notice hundreds of ugly faces leering from its sides.

This 18th-century sundial was designed to calculate the date of Easter each year.

During the summer months, giant teddy bears take over Paris near Les Gobelins metro station.

This bridge was constructed from the rubble of the infamous Bastille.

A 16th-century fountain marks the site of a lost medieval cemetery once filled with mass graves.

A lone cannonball remains lodged in the walls of the Hotel de Sens as a sober reminder of a revolution.

A series of abstract, silly sculptures represent the works of a great modern classical composer.

A Parisian exterminator's shop whose storefront displays stuffed rats hanging from traps.

This life-size replica of the Statue of Liberty's flame is also a tribute to Princess Diana by default.

This former “ante-chamber to the guillotine” has been refurbished to illustrate the brutal history of French justice.

Twelve grave-faced marble angels guard the emperor's tomb at Les Invalides.

The water-powered carriages are long gone, but for over a century this funicular railway has been the fastest route to the highest point in Paris.