More than a million buildings stand vacant across the United States. They're dark, dangerous and above all, they hold secrets to our past that some say shouldn't be forgotten.
A group of New Jersey locals have made it their mission to uncover those secrets, and they've attracted quite a following in the process.
They're known as "Abandoned New Jersey" on Facebook, where they anonymously post pictures and videos of their country-wide explorations.
The first place to kick it all off, however, still holds a special place in their heart: The Essex County Overbrook Hospital.
"It's a little bit weird. It's kind of like a kindred spirit when you meet people in there because you know someone else has the same draw that brought you in there," said one member.
Many of the Abandoned New Jersey members met one another inside the old Essex County hospital.
Today, they know the insides of the 120-acre complex so well that they no longer fear the loose flooring and dark hallways.
"There used to be a tunnel that ran underneath," said a member, describing a series of walkways that ran underneath the old hospital. "You can still see the brick. It's not just a hunk of concrete on the ground. It's a tunnel."
The complex closed in 2007. Some of the buildings are now demolished. Those that remain have become a playground for teens and young adults eager for an adventure.
As a result, police ticket or arrest any trespassers.
"Over the years, they've done everything from hiding in the tunnels to the buildings to setting up cameras in the woods. They've been known even to find people who have posted pictures online and send local police to their house to intimidate them."
But that's not stopping hundreds of people from regularly voyaging inside. And, those that do say the risk only adds to the fun.
"Everything we've done have been some of my fondest memories. We've had so much fun and so many crazy stories. I would lead a very boring life if I didn't do this stuff."