This extraordinary art museum is like a secret world on the edge of Mexico City.

A preserve with 75,000 ancient drawings remains the realm of public – not just scientific – exploration.

An extraordinary house museum and cabinet of curiosities in the heart of Florence.

The remains of an ancient Roman city are hidden underneath Bologna's beautiful public library.

The mountaintop inspiration for Umberto Eco's "The Name of the Rose."

The studio built by fascists in the hopes of "reviving the film industry" with the occasional propaganda film opportunity thrown in.

Venice's island of the dead.

Over 50 exquisite hand-painted Renaissance maps decorate a Medici storage room.

The engineering wonder and pleasure dome of a much-maligned emperor still holds undiscovered secrets.

Rome's semi-secret peephole vista is also a former Crusader stronghold.

Inky sludge oozes to the surface of this beach thanks to a rare natural tar seep.

This influential Renaissance-era library was once the haunt of kings and monks.

These magnificent city walls rise from the barren sun-baked Spanish plains like something straight out of a fairytale.

World's oldest operating science fiction and fantasy club, once home to Ray Bradbury and L. Ron Hubbard.

One man's vast collection of artifacts and ephemera from matchbooks and postcards to vintage neon signs and cars.

This spectacular track has run continuously since 1882.

A jaw-dropping "megalibrary" that turns book-browsing into a geometric adventure.

Crypt mausoleum in cathedral's basement contains relics of third century Roman martyr, Saint Vibiana.

Henry Ford's failed rubber plantation in the middle of the Amazon rain forest.

The marble facade hides a little-known medical museum with early surgical instruments and rare copies of canonical texts.

Explore the quarry where the marble was sourced for Michaelangelo's David.

James Turrell's total color immersion art installation, hidden on the top floor of a luxury handbag shop.

The beautiful 1920 Pantages Theatre remains hidden just underneath the LA Downtown Jewelry Exchange.

An unassuming, powerful monument north of the U.S. Capitol bears witness to the resilience of Japanese Americans during a time of grave injustice.