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

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

This charming candle shop has been in business since 1789.

Ring the bell to enter a bar that looks equal parts museum and old curiosity shop.

The world's oldest bookshop still in operation.

The stunning interior of this Gothic church is covered in ornate gold details.

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

A bookstore dedicated to the intersection of comedy and art.

Occupied for six centuries by Franciscan Order nuns, this monastery is an amazing ode to Catalán Gothic architecture.

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

Read a book with a glass of wine at this classically restored bar.

This home designed for chocolate magnate Antoni Amatller is an exquisite treasure-box of Catalan Modernism.

A once grand hotel now sits eerily abandoned in the Catalan countryside outside Barcelona.

A once-secret library of Freemason history in Catalonia.

The 2,000-year-old Roman columns are hidden within Barcelona's Gothic Quarter.

Mountain where Jesus was first tempted by the Devil.

One of Antoni Gaudí's most classic buildings is well-known for its "dragon-back" design.

The world's first clock to use set theory as a measure of time required the invention of a new light bulb just to maintain its obtuse measurements.

Puppet theater and museum holding a collection of more than 300.

This Berlin island is home to a flock of free-roaming peacocks, as well as a historic ivory folly.

A tour of underground Berlin takes you through WWII air raid shelters and tunnels used to smuggle people out of East Germany.

The final resting place of more than 200,000 people, this is one of the largest cemeteries in Europe.

This Japanese treats shop may have been the first business to mass-produce fortune cookies in the United States.

Floating man-made island and upscale restaurant.