The mystery of the Putim Ossuary involves a tricorn hat.

The crypts of Capuchin friars decorated with the bones of over 4,000 friars, including an entire "crypt of pelvises."

An Austrian house of bones filled with hundreds of intricately painted skulls.

Structure built from the skulls of vanquished foes.

A church of bones, decorated with 40,000 human skeletons.

Salt is slowly eating away this abandoned saltworks town in the desert.

Gigantic Romanian salt mines used to heal respiratory conditions.

This extraordinary geological oddity resembles human-made pavement.

A turn-of-the-century architectural marvel built on healing mineral springs and salt licks.

Home to Hollywood history and a very special salt crystal.

This German museum devoted to the simple wonders of salt is actually built over an old saltworks.

This Peruvian canyon is filled with geometric salt pools that have been being harvested since the Incan empire.

Over a thousand feet beneath the Detroit streets is a subterranean metropolis few are allowed to enter.

The world's oldest known salt mine.

The world's second largest salt mine, said to have been discovered by Alexander the Great's horse.

Dress up like a miner and take a slide into the disco-lit depths of this once foundational salt mine.

Poland's oldest salt mine has nearly everything one needs to live underground forever.

An underground city of salt.

Come for the speed, leave in love with the desert.

One of the world's largest salt caves is filled with fragile salt sculptures, salt rivers, and huge salt megadomes.

A sacred lake composed of over 300 separate pools of highly concentrated minerals.

An Australian lake whose pink hue defies scientific explanation.

Salt cured mummies continue to turn up in this Iranian mine.

A salty cave excavated by elephants and the location of a deadly disease vector.