An extensive collection of reliquaries containing the bones of saints housed in the largest Catholic church in Venice.

One of the world's oldest working clocks is curiously missing the Zodiac sign of Libra.

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

A treasure trove of Renaissance-era funerary art in a Roman church built on top of Nero's grave.

This mosaic-lined medieval church was built by the world's first admiral and still holds mass in ancient Greek.

Inside this McDonald's you can dine on your Big Mac and fries next to a 2,500-year-old Roman wall.

Hidden behind a wall, Spanish nuns distribute their signature sweets on a revolving tray.

The only urban monument in the world designed by the great surrealist painter Salvador Dalí.

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

Over two centuries old and counting, Madrid's massive botanical garden contains one of Europe's only desert environments.

Madrid's romantically ornate crystal palace has been offering shelter to plants and art for over a century.

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.

A whimsical bridge adorned with decorative dragons.

This one-time health resort was used by aristocrats around the world.

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

This Stockholm light tower can be controlled by anyone with a smartphone.

340-foot statue built to honour the Heroes of the Soviet Union.

Stalinist skyscraper built with help of cryotechnology.

World's largest bell sits on the grounds of the Kremlin in Moscow.

The tallest hotel in Europe.

Former headquarters of the KGB.

The gorgeous entrances into the city's underbelly look more like grand halls than subway stops.

This building holds the embalmed remains of the leader of the Bolshevik Revolution.