The tradition of open-air secondhand and antiquarian bookselling in Paris dates back to the Renaissance.

A floating cat sanctuary on an Amsterdam canal.

This clifftop arch is a natural stunner.

Drink wine handed out through a window as part of an age-old tradition.

The glowing blue Nymphaeum of Emperor Tiberius.

Summer in Scotland begins with a spectacularly wild and colorful event rooted in ancient pagan traditions.

This quaint Italian town keeps losing ground as the sides of its plateau slowly erode.

The heads of two giant mythological water horses honor Scotland's horselord past.

A church that bred legends, and served as an inspiration for the Da Vinci Code.

Near the former site of numerous witch burnings, this lavish Edinburgh mainstay pays homage to Scotland's brutal history.

A museum dedicated to one of Paris’s most famous residents, tucked into a corner of one of the city’s most famous squares.

A peculiar mansion built by the troubled heir to the Winchester Rifle Company fortune.

In all of the 29 years it was in operation, no prisoners ever escaped successfully... or so they claim.

An artsy hidden staircase leads to breathtaking views of San Francisco.

An early 20th-century bullring converted into a modern shopping center.

The largest Art Nouveau complex in the world is a Barcelona hospital with a 600-year-long history.

Step inside the first house designed by Catalan architect Antoni Gaudí, considered to be one of the first Art Nouveau buildings.

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

Built to give thanks for the passing of a plague epidemic, this cathedral is a one-of-a-kind architectural hybrid.

This whimsical fountain pays tribute to Toronto's four-legged friends.

A 98-room castle in the middle of Toronto that bankrupted a 19th century electricity multimillionaire.

A botanically themed auditorium blooms within the world’s last operating double-decker theater.

This lovely, if imposing, piece of Canadian gothic is possibly the most photographed hotel in the world.

An immersive projection art installation uses sound, scale, and light to take visitors inside classic works of art.