This California estate was either haunted by ghosts or the Marx brothers.

NASA's leading space science lab started by a co-founder with deep ties to the occult.

"The Hoppiest Place in the World" holds the world’s largest collection of bunny memorabilia and is a singular testament of a couple's devotion to all things Leporidae.

Built by an accountant with a dream of running a grand resort, this estate has sat vacant for over half a century.

It's unclear what caused the fire that led to this opulent hotel's demise.

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

Hiding the longest subterranean river known in the world.

This lovely university observatory continues to sit abandoned since its potential savior was sent to jail for fraud.

A charming 17th-century alley is lined with secondhand bookstores and antiquarian shops.

A mining town, now abandoned, was built in a canyon so narrow that the railroad ran right through the hotel lobby.

This rickety old shed hides a trove of secondhand literary treasures.

The abandoned "Ghost Mansion" was left to decay in the mountains of Northern Italy.

These abandoned grain silos and tunnels are an urban exploration dream.

A lonely medieval monastery on an uninhabited island.

A haunting theme park is slowly being swallowed by the jungle.

This small city where almost everyone lives in the same building can only be reached via North America's longest tunnel.

This WWII-era military installation once held an entire city within its walls - now, its walls are falling down.

The site of one of Japan's very few American occupations during World War II still holds the relics of a roundly disastrous campaign.

An abandoned asylum once on the cutting edge of lobotomies may be reborn as a Christian college.

A recently abandoned psych ward at the end of Sanatorium Road.

An abandoned boat that's been stranded mysteriously for decades.

Local legend says the remains of Father Christmas lie within the medieval grounds.

One of the world's largest automobile junkyards is a unique landscape of metal and moss.

A peat bog in southern Sweden provides a cozy and photogenic home for junked Volvos, Saabs, and the occasional American muscle car.