The vast, legendary catacombs hold secrets much stranger than stacked bones.

The resting place for anonymous victims of the Danube's dark waters.

This former insane asylum now holds a pathological anatomy museum.

The former home of an Italian artist is now a shrine to his ambitious works.

A wunderkammer of curious objects and intriguing art nestled within a hub of ancient Roman sites.

A mysterious chasm in the heart of the ancient Roman Forum, the Lacus Curtius was once believed to be a gateway to hell.

One of several skulls claiming to belong to the beheaded St. John the Baptist is on display at this Roman church.

The popularity of Sherlock Holmes led to the creation of his fictional address, turning the orderly London street numbers askew.

Two hundred tons of pioneer artifacts were painstakingly recovered from a shipwreck at the bottom of the Missouri River.

Collection of skeletal systems from the "world's leading supplier of osteological specimens."

This former mining town was named the most toxic town in America.

A wonderful collection of all things Oz is nestled in the heart of Kansas.

A hillbilly theme park that proved so unpopular the land wouldn't even sell on eBay after it closed.

This haunted hotel built on natural springs once served as a hospital for a quack doctor promising a cure for cancer.

The history of the treatment of mental illness, illustrated in all its gory detail, and housed in an asylum.

A piece of John the Baptist in the American heartland.

Four, 18-foot-tall badminton shuttlecocks lie scattered about the lawn of a Kansas City museum.

Community bookshelf of 25-foot-tall book spines.

The "World's Largest Underground Business Complex," a 55,000,000-square-foot city underneath Missouri.

A museum celebrating the Victorian obsession with hair art.

A mysterious light of unknown origin on the backroads of Missouri.

Once one of the world's great cities, Cahokia was a place of religious worship, trade and mass human sacrifice before being mysteriously abandoned.

The show pony of cave systems, Fantastic Caverns manages to live up to its name.

European castle ruins in an American state park are actually the product of death and grief.