Duluth manuscript museum has old, obscure documents. Then there is the historical loot tucked into the walls.

DULUTH — The founder and namesake of the Karpeles Manuscript Library Museum, a quiet place for old, obscure documents, couldn’t have known that there was a copper box packed with even more history tucked into the stone walls of his own building.

David Karpeles, who died in 2022, spent decades collecting manuscripts by some of the world’s great thinkers and doers — brittle sheets of handwritten words by Albert Einstein or pieces of music by Mozart — that he displayed at his museums around the county. Decades before he bought the former church that would become his Duluth locale, members of the First Church of Christ, Scientist, had tucked their own history into the cornerstone.

The museum’s local director, Matthew Sjelin, was recently tipped off about the time capsule that had been sealed into the building’s exterior when it was erected in 1912. He only ever met his late boss by phone, but Sjelin has a hunch Karpeles would have been interested in this find.

“David would have been tickled pink,” Sjelin said during a recent visit to the church-turned-museum.

The time capsule has been extracted, its metal top peeled back like the top of a tuna can, its contents gently unpacked with white gloves. The find, which coincides with the museum’s 30th anniversary, offered a reason to throw a party Saturday. The museum celebrated its milestone year by unveiling the time capsule, along with kid-friendly activities, music and cake.

David Karpeles lived for a while in Duluth and graduated from Denfeld High School in 1953. He attended the University of Minnesota Duluth, then the University of Minnesota, then settled in Santa Barbara, Calif. He had a varied career that included real estate ventures and inventing a program that could read handwriting on bank checks.

He began collecting manuscripts in the 1970s. He was intrigued after visiting a museum and seeing the way a letter written by a famous name, with errors in the text crossed out, made historical figures more relatable to his children.

Karpeles’ first piece was “The Prisoner of Zenda,” an 1894 adventure novel by Anthony Hope. At the time of his death, he had more than a million manuscripts, believed to be the world’s largest private collection.

“It became an addiction to him,” said his daughter, Cheryl Karpeles Alleman, who lives in Florida. “He had a collector personality. He took his earnings and he started buying priceless manuscripts that changed or shaped our history.”

Karpeles opened manuscript museums across the country — places where he could showcase the pieces in rotating exhibits, like sketches of designs from “Star Trek: The Next Generation” and a certificate proving that Amelia Earhart was the first woman to fly solo across the Atlantic Ocean. Entry to Karpeles museums is always free.

Karpeles bought an old Duluth church in the 1990s, adding a museum in the city where he was raised and where his parents still lived. Thirty years later, the space off of downtown and a block from a main thoroughfare retains its quiet, churchlike interior, from its rounded stained-glass windows to its balcony to its pews angled toward a piano. The museum doesn’t quite rank among Duluth’s more high-traffic attractions, but it has its niche — including visitors from local hospitals, locals with an eye on the quarterly rotating exhibits and, according to the guest book, people from as far away as New Zealand.

On a recent afternoon, a man from Las Vegas dropped in with two adult sons. Christian Kolberg, who works in charity auctions, is known in his family for always finding the quirky spot to stop. This is a go-to in Duluth.

“This place,” he said, “is a treasure.”

Much like this weekend, the time capsule was the main event of a morning ceremony in late October 1912, when members of the congregation started building the church at 902 E. 1st St. An article in the Duluth Herald highlighted the copper box, its tightly packed contents described as “literature of the day especially interesting to Christian Scientists.” They will now be on display at the museum.