For decades, Puerta del Sol has been illuminated by a giant, guitar-wielding bottle of sherry.

Madrid's last horchata kiosk is a blue-and-white beacon of refreshment.

A whimsical brother of the nearby Fallen Angel statue takes the falling part quite literally.

A lush indoor jungle fills this bustling Madrid transportation hub.

Abandoned for decades, trains still pass through the now-restored remains of one of Madrid's first metro stations.

The oldest restaurant in the world is this old-world Spanish eatery, still known for its suckling pig.

James Turrell's total color immersion art installation, hidden on the top floor of a luxury handbag shop.

A collection of haunted objects and macabre oddities under one roof.

Hundreds of hidden passageways weave through the old quarters of Lyon.

This massive library holds what was once the largest book collection in the world.

Notorious artist squat renovated into legal studios.

Abandoned railway line circling the city of Paris.

France's most famous cemetery, with some of its most curious tombs.

The floor of this spectacular Baroque sanctuary is covered in memento mori.

Stone Age solar temple is aligned with the sun on each equinox and solstice.

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

This building has a giant piercing through one of its corners.

Some people believe that this makeshift space monitoring station received transmissions from clandestine cosmonauts.

This Torino museum honors a soldier who kept the city safe using barrels of exploding gunpowder, losing his life in the process.

A fake medieval village in the middle of Turin.

The astonishing collection of an infamous criminologist.

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

An alchemist's "magic door" stands in the middle of a Roman park.

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