World's first "penitentiary," meant to be humane, drove men insane.

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

This homegrown adoption center offers a wonderland of feline companionship.

The hotel where Martin Luther King Jr. was shot is now a museum dedicated to his work.

This head-spinningly bizarre Depression-era art cave is wall-to-wall quartz and Jesus.

An unmarked, overgrown path through dense vegetation leads to the largest ancient structure in Polynesia.

The world is full of swimming holes, but few compare to Samoa’s idyllic To Sua ocean trench.

The fully functional, submerged Vanuatu Post Office is definitely one of a kind.

This South Pacific volcano has been blowing its stack for over 800 years and is said to be home to a cult leader waiting to be reborn.

A charming "tea atelier" hidden away in Greenpoint, Brooklyn.

HBO series' stage tucked away in a Greenpoint lot is the largest theatrical set of its kind in the United States.

On the top floor of an upscale department store stands a lavish restaurant housed in a replica of a luxury French dining car.

Hungarian self-built castle.

Castle and secret tunnel withstood a siege until its owner was killed by the Holy Roman Empire, while sitting on the toilet.

This "dead marsh" sits among the largest sand dunes in the world, a forest frozen in time.

The remains of diamond fever taken over by the desert.

This fairytale castle was built as a show of power but was nearly torn down thanks to its history of torture.

This throwback amusement park is home to rides and unique storybook figures from the past.

This Dresden church was purposely rebuilt Protestant after being demolished in World War II.

The largest Neolithic ruins in the world hide a notably clean prehistoric metropolis.

This Costa Rican topiary park is a surreal garden of unearthly delights.

This abandoned asylum was once a state of the art facility before devolving into one of the most deadly mental institutions in American history.

Fortified homes of highland warriors that are still in use today.

A swing to dangle you off the very edge.