Reservations are required, but ghost hunters are welcome to bring infrared cameras, night-vision goggles, thermal-imaging devices and other high-tech equipment to record images or unexplained sounds in the historic prison, which opened in 1896 to 150 inmates.
Susan Nirode, operations manager, said the preservation society marked a decade of ghost hunts in 2008. The prison has been featured on the "Ghost Hunters" series on the Sci-Fi Channel and was included in a segment titled, "Scariest Places on Earth." Last year it was featured on The Travel Channel's "Most Terrifying Places in America."
The architecture and imposing landscape make the reformatory a spooky setting.
The 250,000-square-foot prison is constructed in three architectural styles -- Victorian Gothic, Richardsonian Romanesque and Queen Anne. It contains the world's largest free-standing steel cell block with six tiers and 600 cells. The facility is listed on the National Register of Historic Places.
Visitors also come because of the Hollywood connection.
Much of "The Shawshank Redemption" was shot at the prison in 1993. "Air Force One" with Harrison Ford also had scenes filmed at the prison in 1996. "Harry and Walter Go to New York" and "Tango & Cash" also featured the prison.
But who comes looking for ghosts?
"It ranges from people who have never ghost hunted to very professional paranormal teams that come in," Nirode said.
No one is permitted to bring Ouija boards or hold seances inside the prison.
"There is a belief that boards bring in something we don't want here," she said. "There's just too many unknowns in this world, and we don't want to take that chance."
Mike Middleton, who has provided ghost hunt tours for the past two years, has many hair-raising stories to share with visitors, including sightings of a "shadow man" documented on an infrared camera set up in solitary confinement.
Middleton has compiled 400 EVPs -- in ghost hunt lingo, that's "electronic voice phenomenon" -- which he has recorded on tape.
"We take this evidence seriously," Middleton said, playing some of the disembodied voices on his tape recorder. The noises are interpreted by paranormal investigators as the voices of ghosts or spirits.
Nirode added that during ghost hunts, nothing inside the prison is manufactured to purposely scare people.
Scott Sukel, ghost hunt manager, seconded that.
"We have seen, heard and felt many things we cannot explain," Sukel said.