This whimsical castle of grottoes was the labor of love of a French postman, and one of the greatest achievements of outsider architecture.

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

North Central Florida's largest flea market and a weekend roadtripper's dream.

A giant donut stands as a popular symbol of Los Angeles iconography.

This floating cinema brings new meaning to the phrase "going out" to the movies.

Walk upon the mementos of the dead in this Parisian courtyard paved with medieval tombstones.

Museum dedicated to literary greats of the Romantic Period is also the home in which Keats met his untimely end.

This iconic L.A. bookshop is housed in an abandoned bank—both symbolic and chic.

Medieval museum built over Roman baths that features famous tapestries of a lady and a unicorn.

An architectural oddity of six stories, accessed by graceful ramps.

The hidden "ballroom" under a mansion lake was built by a criminal who ate a cyanide pill during his trial.

One of the most beautiful bookstores in the world hides a neo-Gothic interior behind an art nouveau facade.

On Japan's Tashirojima Island, cats are king.

Drinkslinger is an unlikely vocation for a Buddhist monk, but at this Tokyo bar the enlightenment is served in a martini glass.

High-end antique collection housed in a centuries-old church.

A rocky sea serpent hides caves, blowholes, and a spectacular natural bridge.

This hospital once pioneered the use of electroencephalograms, but fell into maltreatment, abuse, and eventual abandonment.

Where an entire elephant skeleton, a snakeskin table runner, and thousands of animal remains become art.

The largest underground church in Europe.

A limestone wonderland of water and subterranean secrets.

Brain collection and database that narrows the gap between man and animal.

A tribute to the life and work of the beloved "Peanuts" cartoonist.

Nestled in the heart of San Francisco’s bustling Financial District stands a unique homage to the Mayan and Beaux Arts.

A fernery hidden by neglect is uncovered, and an ancient specimen along with it.