The old tuberculosis sanatorium, long since closed and crumbling on the outskirts of Duluth, was an irresistible lure to everyone from history buffs to ghost hunters.

Ignoring the “No Trespassing” signs and live-in groundskeepers, curiosity seekers over the years kept sneaking onto the grounds of the Nopeming Sanatorium complex. Not only did they endanger themselves, more often than not they did damage to a historic site that preservationists hope someday to put to good use again.

Then Nopeming’s caretakers hit on an idea. Instead of chasing curiosity seekers away, they would invite them in.

First came the ghost hunters.

“We are at the Nopeming Sanatorium, where thousands were infected with tuberculosis, a killer disease,” paranormal investigator Zak Bagans intoned, introducing viewers of the Travel Channel’s “Ghost Adventures” to the splendid, spooky ruins of Nopeming. The episode, which aired last year and is available to stream on Netflix, was full of atmospheric shots of peeling paint, gory re-enactments of tuberculosis surgeries and too many jump scares to count. Nopeming, Bagans assured his audience, is “a massive and tragic place of death.”

It’s also a pretty fun place to spend an evening, as a growing number of visitors have learned. Guided tours started last month and tickets start at $22 for a one-hour day tour of the site, $25 for a spookier night tour — bring your own flashlight. Enthusiasts also have the option of booking longer “paranormal investigation” tours.

Cynthia Nash, who has lived in the Duluth area for the past 13 years, had no idea the sanatorium was there until her teens watched the “Ghost Adventures” episode. She booked the family on a night tour and spent a hair-raising evening prowling the dark, clammy corridors.

“It was actually very fun,” said Nash, a nurse who has since talked with colleagues who remember Nopeming from its stint as a nursing home in the 1970s. The facility proved too expensive to maintain and was shuttered in 2002.

The tour includes the sanatorium grounds, patient rooms, empty hallways, the chapel, the post office, the kitchen and the auditorium. Visitors edge through darkened hallways full of peeling paint and ominous shadows. Nash’s kids loved it.

“It’s spooky, it’s historic. ... I absolutely would recommend it,” she said.

Nopeming, an Ojibwe word meaning “in the forest,” has stood for a century on a remote hillside, surrounded by 40 wooded acres. The only part of the property visible from the highway is one towering chimney. For generations, places like Nopeming offered tuberculosis patients rest and fresh air — the only real treatments available before the discovery of antibiotics — as they battled the infectious, often fatal, disease.

People have been trying for years to give Nopeming a new purpose.

The site’s current owner, the nonprofit Orison Inc., hopes to start small, by renovating the Nopeming auditorium into an event space.

“We are planning to slowly renovate sections of the property, one at a time,” project director Tanya Graysmark wrote in an e-mail. “Our goal is to eventually reopen all of Nopeming and provide Duluth and the state of Minnesota with a historical, viable, sustainable, property that serves the community to its best potential.”

Tours will continue into the winter, weather permitting. For more information, visit www.nopeming.com.