The water here is so clear you can see the mysteriously sunken ship from the surface.

The remote outlaw hideout of Jesse James, Butch Cassidy, and the Sundance Kid.

The first Russian Orthodox church in the Catholic city of Rome in almost a thousand years.

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

Milan's duomo is covered in beautiful carving including a curious "dinosaur-like" beast.

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

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

London's creepiest cemetery was once the site of dueling magicians and mobs of stake-carrying vampire hunters.

This unreal Portuguese palace looks as though it's made from a pile of different castles.

An ancient and majestic fortress that played an integral role in Portugal's road to independence.

A memorial in the Tiergarten is a reminder of the suffering inflicted on homosexuals by the Nazi regime.

This narrow Ghent alleyway is an officially sanctioned street art tunnel.

The ritual has been performed uninterrupted for nearly 700 years.

The commemorative stone column conceals a secret laboratory.

The Great Fire of London and the regulation of one-way streets both started in this alley.

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

These "mermaids" that surround a plaza in Segovia are rather sphinx-like.

Special benches that play Chopin's music are scattered throughout his native city.

The giant statue and its model solar system honor the native Pole who declared that the Earth revolves around the Sun.

The Polish capital has had a deep connection to its guardian mermaid for almost a millennium now.

A menacing statue of this mythical creature can be seen at the legendary site of the monster's lair.

A tribute to the Polish insurgents who fought in the failed attempt to end their city's Nazi occupation.

This colorful and quirky set of pegasus sculptures celebrate the works of poet Zbigniew Herbert.

Legend has it that Napoleon Bonaparte fell in love with this Gothic church.