The second-largest cave chamber in the world was discovered in 1898 by a 16-year-old and a friend known as "Pothead."

A particularly creepy abandoned hospital that sparks interest for lovers of the supernatural.

A museum dedicated to the alleged Roswell Incident.

The one-stop shop for all of your superhero (or evil arch-nemesis) needs.

Take a drunken tour inside the world's largest known geode.

The world's longest known cave system.

This massive stained-glass masterpiece is thought to be the largest Tiffany dome in existence.

In the middle of an extremely unforgiving and desolate high desert is the most secret military facility in the world.

Four glass boxes hover over 1,000 feet in the air to give visitors an unparalleled view of Chicago.

Paranormal experiences in this hotel's room 217 led Stephen King to write "The Shining."

Its buzzing collection honors vibrator history.

The site of the climactic scene from the classic horror film is now a historic landmark.

A 100-year-old purveyor of curiosities, curios, and kitsch featuring mummies, shrunken heads, and a Fiji Mermaid.

A walk through the historic city center, under the streets of Seattle.

A 140-year-old castle with underground caves hidden in San Francisco.

The inspiration for H.P. Lovecraft's horror stories and Batman's Arkham Asylum is now a condominium complex.

This abandoned subway station beneath the Waldorf-Astoria hotel is allegedly used to secretly transport presidents.

High on a hill overlooking Los Angeles lives a world famous, high power conical Tesla Coil.

A bizarre house filled with an astounding array of collections.

Tucked in the back of this amazing antique store is an important piece of medical history.

A crumbling hospital from the 1850s on Roosevelt Island.

The neon signs from Las Vegas' past find their final resting place at this unusual graveyard.

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

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