This charming cobbled backstreet is the most Instagramable street in Paris, much to the residents' annoyance.

This modest marker near Notre Dame identifies the very center of Paris.

Paris' linguistic guide to the international language of, yes, love.

This iconic Parisian bookstore doubles as the "Tumbleweed Hotel" for traveling writers.

Abandoned railway line circling the city of Paris.

Notorious artist squat renovated into legal studios.

This inexpensive lodging house was once a prison notorious for its inhumane practices.

Faceless white figures loom over the city from the rooftop.

Not merely a museum – but a whirring powerhouse that offers a subterranean peek into the heart and soul of cable car operations.

This private residence was the template for one of the most beloved television homes of all time.

A collection of memorabilia from the Beat era in the back of a San Francisco bookstore.

Tiki luxury on Nob Hill.

A collection of 20th-century automata, penny arcade games, and musical contraptions.

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

A psychedelic labyrinth on the San Francisco bay.

A school teacher's massive and terrifying self-built castle.

This Niagara Falls tourist trap is a world bright with neon and curiosities that will inspire love, hate, or a mixture of both.

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

Few other hotels can rival the grandeur of the Castle in the Rockies.

A grand Gothic Revival basilica with stained glass depictions of Montreal's religious history has only one soul resting in its crypt.

This expansive bridge in the Canadian wilderness was originally just built for friends.

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