One of Antoni Gaudí’s earliest buildings, built between 1886 and 1890 for the industrialist Eusebi Güell.

Sip cherry liqueur at a bar dating back to 1840.

Get in line for Lisbon’s most famous sandwich.

This Industrial Age architectural and engineering gem helps visitors and residents alike traverse Lisbon, “The City of Seven Hills.”

The world's oldest bookshop still in operation.

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

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

Picturesque intersection of witchcraft and ancient Christianity.

One of the most beautiful bookstores in the world hides a neo-Gothic interior behind an art nouveau facade.

This restored Portuguese cafe may well be the most beautiful place in the world to grab a Big Mac.

Elaborate tile work in this railway station tells the story of Portugal.

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

A fortified palace in the shape of a ship on the Thiou river.

This modern French ossuary contains the jumbled bones of 130,000 WWI soldiers.

Site of one of World War I's most horrific scenes.

A university observatory dome painted to resemble the beloved 'Star Wars' droid.

The sweet story of how American cargo planes became known as "Candy Bombers" during the Berlin Blockade.

Fantastic views and thousands of love locks.

From Nazi chemicals to the CIA, this architectural marvel has played a fascinating role in German history.

Devious political maneuvering and four ancient, working telescopes are central to the world's second-oldest observatory.

One of the Leiden's oldest pubs is also the birthplace of the Heineken star.

The works of poetry's biggest names grace the walls of the city of Leiden, all carefully painted by hand.

Science meets wall art to highlight the beauty of famous mathematical equations.

A 'living museum' in Leiden, the oldest of its kind in the Netherlands.