Danish tourist destination well known for open stalls where vendors sell marijuana on the street.

Inspiring Herman Melville and Henry David Thoreau, Mount Greylock in western Massachusetts is the highest point in the state at 3,491 feet above sea level.

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

Avoid gangster interaction while window-shopping.

A little-known subterranean street runs under some of the best-known buildings in Chicago's River North.

Naturally formed white marble arch housed in an abandoned marble quarry from the 1800s.

A 12th-century fortress containing some of Berlin's oldest buildings.

This "floating railway" is one of the world's oldest monorail systems.

Giant, friendly pelicans in Central London, the most unlikely of places.

First a horse rendering plant, then a 19th century landfill, this beach is full of glass from thousands upon thousands of broken bottles.

The John Snow Memorial marks the epicenter of London's 1854 cholera epidemic.

The site of one of the strangest disasters in history—a wave of deadly molasses traveling at 35 mph.

Six ravens are kept captive (but well-fed) at the Tower of London to prevent the fall of the Crown.

One of the steepest streets in the United States makes an intriguing challenge for cyclists.

The highest peak in the United Kingdom has a history of physics, specters, and a pilgrimage of strange objects.

The fanciest public restroom in New York City boasts fresh flowers, art, and a classical music soundtrack.

The United States’s oldest funicular railway glides up and down a steep Pittsburgh street.

The enormous 250-room Vanderbilt mansion conceals hidden doors and secret passageways.

A Parisian cemetery where the elite and artistic are interred beneath an eccentric collection of tombs.

A pedestrian island in the middle of world-famous Times Square emits a strange (and purposeful) humming noise.

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

This unmarked and unloved Manhattan subway grate created one of the most iconic images in American cinema.

An antiquated German apothecary on Chicago's North Side.

The curiosities and wonders of pharmacy in a delightful historic building.