It is said that each of the white stones in the red facade of this medieval house represents the head of a murdered Swedish noble.

An ancient Viking runestone hidden in plain view in Stockholm's old town.

This homeless brass fox tugs at your heartstrings from the foot of a Stockholm bridge.

Stockholm's deepest subway station is also a stunning ecological wonder.

The library's graceful rotunda is like a bibliophile's temple.

It houses the remains of a 17th-century version of the Titanic.

Stockholm's decidedly unique public transit system has doubled as the world's longest art gallery for decades.

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

An ossuary built in 1210 to collect bones from the Ospedale Maggiore of Milan.

This cathedral hides a sculpted dog that determines your fate and an unexploded shell from World War II.

Massive galleon from a box-office bomb docked in Genoa.

This sweet-toothed bear searching for snacks has been a symbol of Madrid for decades.

Remarkably intact Roman stone fortifications have encircled this Spanish city for centuries.

Giant granite sculptures representing family on the northern coast of Spain.

The oldest Roman lighthouse still in use.

The iconic boulevard is the perfect place to catch sight of a bicycling skeleton, a levitating Satan, or a chef with his head stuck in a pizza.

The world's largest wooden structure.

Gaudí's famously flamboyant architectural style is on full display in this sprawling park and garden.

These secluded and abandoned anti-aircraft defenses have become one the most scenic viewpoints in Barcelona.

One of Antoni Gaudí's most classic buildings is well-known for its "dragon-back" design.

Construction of Barcelona's iconic (but controversial) church is expected to be completed in 2026—a century after the death of its architect.

This castle has links to Portugal’s founding and struggles for independence.

This giant sculpture made of trash is a critique of society's wastefulness.

Hidden beneath a beautiful overlook you’ll find the history of the city depicted in comic strip format next to a pay toilet.