Amsterdam's Red Light District leaves little to the imagination.

In the days before house numbers, these colorful signs held clues about various buildings' purposes.

The former home of a mad diplomat is said to still be marked in bloody, arcane scrawls.

A rare tour of an aristocrat's private home reveals valuable 17th-century paintings from artists like Rembrandt.

The history and future of cannabis.

The world's first zoo for microbes collecting the horrible and wonderful things living on and around us.

A curious collection dedicated to human and animal anatomy and pathology.

A collection of more than 12,000 shoes, displayed in a building shaped like a shoebox.

One of the Seven Wonders of the Modern World holds the world's tallest metal staircase.

The Victorian-era greenhouse is stuffed with tropical plants, and open 365 days a year.

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

This Greek temple, open only an hour a day, was the site of a war of tastes between an architect and an artist.

For one day every month Barcelona's Estació de França transforms into a market for model trains.

The former 1920s mansion of a prominent Catalan developer was used as the Soviet Embassy during the Spanish Civil War, and there is still a bunker below the garden.

These secluded and abandoned anti-aircraft defenses have become one the most scenic viewpoints in Barcelona.

This cemetery features modernist statues as strange as its name.

Frequent fliers welcome in this airplane hotel.

Early habitat dioramas and home of the elusive gaff, the skvader.

A living art gallery painted on a canvas of Monterey pine trees.

Mysterious tombstones thought to be remnants of Atlantis.

The titular "little arch" near this Italian resort is one of the most popular diving spots in the country.

This mysterious Sardinian festival sees a horde of blank-faced equestrians compete for tin stars.

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

The former private quarters and office of Dr. Sigmund Freud now hosts a museum housing the works of the founding father of psychoanalysis.