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

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

A whimsical bridge adorned with decorative dragons.

Built in 1870 at the bridge that connected Buda and Pest, this spectacular incline railway was almost lost forever during World War II.

Once an opulent Art Nouveau hotspot, the Constanța Casino is one of Romania's most beautiful abandoned buildings.

This statue of the great Argentinian car driver is located near a famous curve of the Monaco Grand Prix.

Legacy of the earthquake that nearly wiped Lisbon off the face of the Earth.

A king's pet, a pope's gift, an artist's inspiration, and a tragic shipwreck.

Elaborately carved to showcase the glorious wealth that the age of exploration brought to the Portuguese empire.

Eat the ultimate iteration of Portugal's most beloved pastry.

Legend says this sacred tree was a gift from goddess Athena.

A marvel of Byzantine engineering under the streets of Istanbul.

A fountain standing as a testament to a doomed alliance.

An underground network of massive stone arches and their skylit vaults support ruins of portico structures above.

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

One of the best-preserved medieval streets in Europe.

This community on a small Venetian island has taken to painting their houses in bright neon hues.

Go inside to really appreciate this 500-year-old technological masterpiece.

Two stone columns flank the grand Venice square, but there were supposed to be three.

Those who own or stay at this 500-year-old, allegedly cursed house often meet terrible fates.

The ancient heart of Tunis is an enormous maze of narrow streets and alleyways.

Why a column on the entrance is inscribed with a verse from the Quran is one of Sicily's many mysteries.

The world's oldest known salt mine.

Terrifically morbid cemetary and site of famous Paracelsus' grave.