No one is sure if the world's fourth-largest diamond had been found in a rubbish heap or was pawned by Napoleon's mom.

The most metal church of all time was built in record time because of an international, pious pissing contest.

A gorgeous, Gaudí-esque stairway constructed in the city of Istanbul by a prominent Jewish family.

Legend says if you stick your thumb in the hole and it gets wet your wish will be granted.

This remarkably well-preserved Egyptian plinth is pretty well traveled for a giant piece of stone.

A meow-velous tribute to a beloved street cat, made famous on the internet.

A small etching on the white marble parapet was written in runic script by a Viking mercenary.

A secret hatch containing two parchments was discovered in this statue over 40 years after its installation.

A massive marble foot is tucked away in a small alley near the Pantheon.

The only remaining arch of the oldest stone bridge in Rome stands in the middle of the Tiber.

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

A detailed pachyderm supports Rome's smallest Egyptian obelisk.

This hydrochronometer was invented by a Dominican monk and is a prime feature in this garden.

A new sculpture calls attention to climate change in the centuries-old city it threatens.

Two stone columns flank the grand Venice square, but there were supposed to be three.

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

Nestled in the heart of Milan is a real wunderkammer of morbid curiosities.

A larger-than-life house of cards stands outside the house of a former fashion designer.

Before there were doorbells this bronze ear was installed for visitors to announce their arrival.

Legend says this mysterious stone head belongs to a woman who was petrified by an alchemist.

This ancient market is often referred to as the oldest shopping mall in the world.

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

A magnificent waterfall is also home to the remains of a Roman hydraulic engineering system.

A sinister pyramid in the Frari contains the heart of the famous neoclassical sculptor.