This huge, disused viaduct is now a crumbling concrete underworld of covered in years of graffiti.

These beautiful ruins deep in the Pennsylvania woods are thought to have been a ski lodge or a speakeasy, but no one really knows.

A macabre farm reserved part of its 222-acres for dead bodies, all in the name of science.

The internal railway of one of the biggest steel plants in America has been transformed into a linear park with unique industrial views.

Pennsylvanian mass grave and possibly mass murder.

A stone arch leads to a cavernous 1930s spring house tucked away in the Pennsylvania woods.

Collection of trolley cars in the woods represent one man's attempt to preserve transportation history.

A park full of outsider art, created by college students studying outsider art.

Buildings that dynamite couldn't bring down were abandoned because of bathroom issues.

This abandoned Poconos resort is haunted by a history of kitschy romance and a violent fugitive.

A modern ghost town whose inhabitants were driven away by the growth of nuclear power.

Sail through this subterranean show cave that is home to a legend that would go on to name nearly everything around it.

Where America's first doomsday cult awaited the end of the world.

An abandoned stretch of highway, deteriorating next to the operational one.

An abandoned cemetery lies in ruins as the surrounding forest swallows it whole.

A toxic ghost town sitting atop a massive coal fire.

A pink and gray pair of pachyderms advertise a fireworks shop.

4,000 monkeys used for medical testing on an island off of South Carolina.

An unfinished rail tunnel that has since been used to house cheese and bats.

This abandoned school has had many lives since the early 1900s, and all of them doomed.

An abandoned 1920s school with a mysterious history.

These rows of World War II-era bunkers were the scene of some of the infamous Mothman sightings.

Beyond the usual stories that attend old prisons, this one has deep bloody undercurrents.

Once connected to the outside world by a single train track, this ghost town is looked after by the National Park Service.