Contractors working to develop a $17 million triplex in a historic TriBeCa building have brought to light a forgotten work by the artist Keith Haring.

The triplex, in the American Thread Building, served as an art exhibition space in 1979, when Haring painted a piece of the ceiling and wall with a pattern of black-and-white line figures and designs. As the years passed and the space became a restaurant and then a dusty storage area, the painting was forgotten.

A senior managing director at Cantor Fitzgerald, Mark Colaio, and his wife, June, later purchased the space, intending to convert it into a high-end condominium. Colaio was killed on September 11, 2001, however. The property was quiet for another two years.

VIDEO: A Forgotten Haring Is Found by Contractors

“It was a mess,” a broker at Sotheby’s International Realty who was shown the space, Lee Summers, said. “But it was authentic, a truly historic space.”

The rest of the building had long been converted into luxury condominiums when a real estate developer, Richard Saunders, bought the property a year ago, and work commenced. Contractors broke through a wall on the second floor and opened a stairwell into the basement, creating a nearly 8,500-square-foot space and unearthing Haring’s work in the process.

At first, Mr. Saunders said, he didn’t know exactly what to do with the painting.

The work was original, according to the Keith Haring Foundation, but it couldn’t be moved because it was painted on fragile firebrick.

“I interviewed a lot of preservationists, but eventually I decided to just let it be,” Mr. Saunders said. The rest of the space was completely renovated.

The room at the entrance, which was used as a trading room for the Wool Exchange in the 1800s, has carved moldings and a 26-foot ceiling. Mr. Saunders had those features restored, a new floor put in, and a $160,000 stairwell added to the second floor, which has two bedrooms and a large bathroom. The basement, home to several restaurants over the years, was transformed into what Ms. Summers said would be an ideal game room and work area.

But the property’s most striking feature is the Haring wall. It is the first thing prospective buyers will see after they enter the apartment from the private door next to the lobby entrance. The wall curves until suddenly it juts in, creating a kind of closet where the painting straddles the wall and part of the ceiling. The entire area around the painting down to the floor remains unreconstructed; one section is old black wood and there are holes in the sheet rock.

The Keith Haring Foundation is recommending that the entire section be covered with a Plexiglas window, but Mr. Saunders said he would leave that decision up to the new owners.

Because the artwork can’t be removed from the wall, Mr. Saunders said, it has not increased the price of the triplex.

“It’s just an added thing,” he said. “It’s for somebody who likes Keith Haring.”

If it were removable, the artwork would be worth between $800,000 and $1 million, he said.

The executive director of the Keith Haring Foundation, Julia Gruen, said the piece dates to 1979, when Haring was 20 or 21. He died of AIDS in 1990.

“This was a project that Keith did using the space,” she said. “He was barely at the beginning of his career, a college student.”

The work is consistent with his early experimentation with abstract pattern making, Ms. Gruen said. The tessellating effect of this piece is present in his more iconic images, which can be found in major museums around the world.

“It’s the same alphabet of images,” she said. “But the work became more graphically direct later in his career.”

A Haring drawing from 1984 recently sold for $400,000, and his less distinct works sell for between $20,000 and $50,000, Ms. Gruen said.
“We’ve had people periodically asking us over 20 years what is this thing” at the American Thread Building, she said. “Now we hope it will be valuable to whoever purchases the apartment.”