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

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

Among the oldest structures in Madrid, these Moorish walls once guarded the medieval city of Mayrit.

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

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

A 1,000-year-old church holds the bones of the Christian martyrs who died hiding inside it.

A long-buried ancient ruin unearthed right in the middle of the city.

Before it was buried by volcanic ash, this fast-food restaurant fed the hungry hordes of ancient Rome.

The walls and streets of the ancient city are peppered with penises.

Erotic art covers the walls of the largest ancient pleasure palace.

Ancient snack bar of the Roman Empire re-opened.

The last moments of the ill-fated Pompeiians, frozen forever in plaster.

These "anatomical machines" are only one of the many strange items in this Italian crypt.

Skulls and skeletons are omnipresent in this church dedicated to souls trapped in purgatory.

People have been living in the cave houses on this Italian hillside since the Neolithic era.

The only museum with its curator—and her pets—buried inside.

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

A sinister pyramid in the Frari contains the heart of the famous neoclassical sculptor.

A 250-year-old timepiece-automaton adorned with golden mechanical birds, which still sing to this day.

One of the world's tallest statues is also one of its most hated.

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

Former headquarters of the KGB.

It took over half a century but a Russian monument to a famous and tragic space pup finally stands in Moscow.

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