A library of rare occult books in Los Angeles.

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

World's largest collection of serial killer artwork and other macabre exhibits.

The huge golden reliquary of a testicle-smashing saint.

A beautiful lighthouse with as many steps as days in the year, as many windows as weeks, and as many levels as months.

The birthplace of the ferocious William the Conqueror, this castle is awash in medieval history.

This statue honors the thousands of Allied avians that served and died for France during World War I.

Bloodstains can still be seen in this medieval church where two medics saved lives on D-Day.

A medieval church with largest and oldest collection of Renaissance frescoes in France.

Hundreds of secret cabinets built into the walls of legendary poisoner's private work room.

This modern French ossuary contains the jumbled bones of 130,000 WWI soldiers.

Hundreds of hidden passageways weave through the old quarters of Lyon.

A cave dwelling that was started by the Celts, expanded by monks, and finished by knights.

Exquisite wall sculptures carved in secret by an early quarryman in an obscure corner of the Paris Catacombs.

Sacked by Vikings, blessed by William the Conqueror, dealt a fatal blow during the French Revolution—these ruins have seen it all.

A subterranean shelter remains intact under a busy Paris railway station.

This 1,300 year old monastery built atop a single rock was once only accessible depending on the whims of the tide.

This massive library holds what was once the largest book collection in the world.

The macabre collection of Jacques Sirgent, an expert scholar on the undead and all of their trappings.

An institution that preserves the history of institutionalization.

Only 68 people per day are allowed to visit this New Zealand bird-watcher’s paradise.

A long-abandoned provincial prison left to crumble in the frigid air of Ontario.

A bright turquoise river cascades beautifully down stepped terraces in southern China.

This greenhouse was once a hockey arena.