This private skyway is filled with art and was expanded explicitly so that Hitler could appreciate a river.

The famous sculptor left his mark on this Italian wall in an internationally protected example of street art.

This bronze boar's snout has been rubbed to a golden sheen by visitors seeking good fortune.

The oldest operating pharmacy in the world features 800-year-old recipes.

A lush indoor jungle fills this bustling Madrid transportation hub.

Memorializing the bravery of one young woman facing the monster of her age.

The modern birthplace of Irish freedom.

A master of trompe-l'oeil creates a stunning, tourist-fooling dome out of a flat ceiling.

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

This Roman arch marks the location of an ancient gate at one of the Seven Hills of Rome.

An ancient knight and a symbol of the city's freedom.

The site of the first medieval crusade that pitted Christians against Christians.

A historic Christian shrine nestled within a spectacular natural cave.

A rather vulgar example of the transition from Latin to the Italian vernacular.

Barça football fans might see the insignia hidden in a church window as a divine sign.

These magnificent city walls rise from the barren sun-baked Spanish plains like something straight out of a fairytale.

The world's largest solar furnace uses 10,000 mirrors to concentrate the sun's rays to generate power.

There is a strange little carving of a person seemingly crushed by a pillar behind the remains of St. Thomas Aquinas.

This Canadian hunting lodge is a long way from home.

This amazing piece of modern art honors the hundreds of fishermen killed during Cambrils' "year of misfortunes."

Famed architect Antoni Gaudi built this generous thank you gift to a friendly host who housed him during a job.

This enormous censer uses a pulley system installed over 400 years ago.

This architectural oddity is an oasis of green on the outskirts of Valencia.

This house's itty bitty size means no humans allowed.