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

Holy Grotto of Montserrat Monastery holds one of Europe's mysterious black Madonnas.

An island filled with hundreds of hanging, decomposing, decapitated dolls.

Legions of Roman soldiers bathed in this ancient spa complex under a Budapest transit station.

A natural history wunderkammer in the middle of the desert.

A 300-year-old tea shop that brought tea to the English people, not to mention the Queen herself.

A lush oasis full of vibrant plants and striking geometric displays.

A small pack of an ancient, hairless breed of dog once believed to guide souls through the underworld lives on its grounds.

The only castle in North America to ever house European sovereigns.

Frida Kahlo's childhood home, now a museum of her life and works.

A wall of this old hotel was decorated with drawings made of pebbles during its construction.

Try the alligator at this fondue spot, which has been catering to "lovers and hedonists" since 1967.

One of the last remaining buildings from one of Calgary's earliest businesses.