Odd outsider art installations surround a Gold Rush-era ghost town.

The same family lived in this Victorian house for nearly 100 years without altering the building.

One of few vertical lava tubes in the world accessible by foot.

Ghost stories surrounded this “castle,” the only structure from a huge mansion that was never built.

This abandoned dream castle and its cemetery look out over the city that once inspired their creation.

This castle was once considered as an option for the Royal Family's alternate residence, but you may know it better from the 'X-Men' movie.

An allegedly haunted mansion with a tragic, tawdry past.

"The House That Love Built" is shying away from "The House That Ghosts Love."

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

A medieval castle in the middle of rural Texas.

This abandoned prison castle has become an imposing gallery of graffiti art.

A museum devoted to bringing to light forgotten or neglected histories through exhibitions, education and public programming.

America's most famous museum of medical oddities is home to the remains of Albert Einstein's brain.

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

An Arizona museum with a collection of pharmaceutical oddities, including a jar of a gangster's chewed gum.

The skulls and bones of thousands of soldiers line the walls of this small Italian chapel.

The astonishing collection of an infamous criminologist.

A 16th century chapel decorated with bones, skulls, and entire bodies hanging from the wall.

An early Portuguese serial killer's head is alarmingly well preserved in a jar at the University of Lisbon.

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

Statue of death tucked in the University of Medicine courtyard.

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

Remarkably preserved body discovered in a peat bog.

These morbid carvings remind churchgoers of the inevitability of death.