Construction began in the fall of 1924 and cost about $50,000.
Although the structure is accessible from Gimghoul Road, it remains a mystery, inspiring nearly a century of folklore.
"It's a mystical thing that's been part of the University for about 100 years," said Roland Giduz, a UNC alumnus and Chapel Hill resident who has researched the castle. "It's part of the heritage of the University. It's really more lore than history."
The most popular legend involves Peter Dromgoole, a man from Virginia who came to UNC in 1833.
Dromgoole fell in love with a Chapel Hill woman, Fanny, but an unnamed man became jealous and challenged Dromgoole to a duel on Piney Prospect, where Gimghoul Castle stands today.
Dromgoole was killed and, as the story goes, buried in a shallow grave under a large rock.
Now called Dromgoole Rock, it sits directly in front of the castle and bears deep-red stains, which some say is Dromgoole's blood.
The facts of Dromgoole's legend have been disputed over the years; one rumor is that he really joined the Army, likely under the name of his roommate, John Buxton Williams.
But the dispute hasn't killed the tale. "The castle itself is sort of a backdrop for the actual story," said Dan Barefoot, a 1973 UNC graduate and author of "Haunted Halls of Ivy: Ghosts of Southern Colleges and Universities," a collection of collegiate ghost stories.
As for the truth of the legend? "That blood stain is still there on that rock," he said. "People can't really explain it."
Besides, he said, "A lot of people claim to have seen ghosts around there."
The name "Gimghoul" was even derived from the Dromgoole story. According to the records of Lyman Cotten, a Gimghoul member who later taught English literature, the "g" came from the word "gargoyle," and "goole" was changed to "ghoul," presumably for a more sinister look.
While the Order always has been a secret organization, members' identities were not as guarded as they are today.
Cotten's records include photographs of the original members, and directories of members from 1889 to 1990 are available in Wilson Library. A list of members even appeared annually in UNC's yearbook, the Yackety Yack.
Giduz said Gimghoul's secrets are no more significant than those of other fraternities. "It's a fraternal order," he said. "Fraternal orders are all secret."
Harry Watson, a history professor and director of the Center for the Study of the American South, said mystery is what keeps people intrigued.
"I'm sure the Gimghouls keep it secret so that people will still be interested," he said.
Regardless of the hoopla, Watson said he doubts the Gimghouls partake in blood-curdling rituals. "I think they just have parties."
And despite his family ties to the society, Watson said he knows only what he has read.
"I was perfectly placed to know all the details about it because my father was a member," he said. "But I never asked him, and he never told me anything except that he was in it. That was back in the days when I didn't listen to what my father said."
The Order was founded in 1889 by Wray Martin, Robert Bingham, W.W. Davies, Shephard Bryan and A.H. Patterson, who all graduated from UNC in 1891.
The men decided to base their society on the Dromgoole legend and ideals of medieval times.
In the early 1900s, a 1900 UNC graduate started plans for a new meeting place; the group had been gathering in a lodge on Rosemary Street.
The castle, finished in 1926, was built by a group of Waldensian stone masons from a small town near Morganton.
The masonry imitates the dry-build style common in 11th-century England.
The inside of the castle, according to news articles from the 1920s to the late 1970s, features walls of the same rough stone and furnishings of hand-forged hardware, moose heads and a bearskin rug.
Today's Gimghoul society is a fraternity that reportedly initiates 10 male juniors a year.
Giduz said Gimghouls have historically been prominent students, professors and alumni.
"There was the idea that it was a very high fraternity in Chapel Hill, in terms of prestige," he said.
Past members include prominent alumni J.C. Ehringhaus, William Rand Kenan Jr., Frank Porter Graham and William Donald Carmichael.
Current members are yet to be revealed - but a little mystery is a good thing, Ferris said.
"I think it's the nature of who we are. We have a love-hate relationship with mystery," he said. "Mystery is still very much alive and well in us, and Gimghoul draws us in because of that."
Contact the Features Editor at email@example.com.