This unattributed sculpture in Amsterdam is hiding in plain sight.

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

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

Where the lovelorn find a home for their sentimental keepsakes.

This Slovak bridge is known both for its connection to a national uprising and its UFO-shaped eatery.

This Slovakian statue of an emerging sewer worker might just be a bronze peeping tom.

Apartment complexes built into huge repurposed natural gas tanks.

Giant WWII fortresses that fired 8,000 rounds a minute, now home to thousands of pigeons.

This former insane asylum now holds a pathological anatomy museum.

One of Catholicism's four major basilicas has a series of papal portraits that are said to predict the end of the world.

This palatial spiral staircase was so unusual the name "snail" was given to the noble family who built it.

Go inside to really appreciate this 500-year-old technological masterpiece.

The final resting place of the poets Shelley and Keats.

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

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

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