The glowing blue Nymphaeum of Emperor Tiberius.

Geothermal waterfalls in Tuscany.

Stalactites and stalagmites in a beautifully lit cave.

Become a prohibition rebel.

This lavish room at NYC's French Embassy is a rare relic from the end of the Gilded Age.

Hidden in Central Park's Ramble is a troublesome cave buried just beneath the surface.

One of the smallest bookstores on the planet.

A counter-culture bookstore like no other hides in plain sight in the streets of Paris.

A quirky bookstore hidden beneath a sea of whitewashed Greek villas.

Pilgrimage site for star-crossed lovers.

The doodles of a genius line the walls of a secret room under the Medici Chapel, where they were hidden for nearly 500 years.

This Venice bookstore has resigned itself to constant flooding by keeping its books in bathtubs and boats.

This symbol of peace is appropriately positioned overlooking the Pacific Ocean.

A fashion designer's dazzling world of Japanese collectibles is hidden in a warehouse downtown.

A spiritual retreat in the heart of Los Angeles offers stunning gardens and a labyrinth to lose yourself in.

Rainbow-hued local gem in Venice.

The hotel room where Janis Joplin tragically died has now become a makeshift shrine to the singer.

The oldest Italian café in Boston, this spot also serves as a veritable museum of vintage coffee ephemera.

A treasure trove of rare and exquisitely detailed antiques

A tunnel once abandoned now thrives with graffiti art as an off-limits makeshift gallery.

A room in New York City that contains 250 cubic yards of dirt worth a million dollars.

A tiny museum housed in a New York freight elevator specializes in the "overlooked, dismissed, or ignored."

A magical place that lets you play in and explore the world of Studio Ghibli.

This London plaque marks the spot where David Bowie's famous alien made his debut.