The gale-force winds of modernism swept America in the 1970s, fanning an overwhelming desire to build anew and modify old buildings.

"New is better. Let's update everything and make it modern," was the attitude, said Noel Zahler, dean of the school of music at Carnegie Mellon University's College of Fine Arts.

So, inside the school's Kresge Theater, where more than 300 concerts and recitals are hosted annually, a large skylit leaded-glass ceiling was removed. That allowed workers to build a state-of-the-art suspension grid from which new lighting was hung.

Then, 35 years passed.

While contemplating another renovation of the 250-seat theater this year, fine arts dean Hilary Robinson urged Dr. Zahler to find out what happened to the glass ceiling. She thought Louis Comfort Tiffany had made it and that it could serve as the centerpiece of a fund-raising campaign to update the theater again.

Dr. Zahler's deputy at the music school, Ross Garin, "literally put on a hard hat and crawled through the bowels of this building," the music dean said.

He found it, broken in some sections, in the basement of the College of Fine Arts building. Laid on a piece of red cloth and covered with straw, it was hidden from view by duct work installed around it when a percussion studio was built.

While the school has no confirmation that the glass ceiling is a Tiffany, its discovery has prompted officials to consider all sorts of ideas on how the theater may be restored and prompted a quest to try to authenticate the ceiling.

If you've never been in the Kresge Theater, it's where the lecture scene was filmed for the 2000 movie "Wonder Boys." The auditorium offers its own visual history in especially amusing graffiti. Starting in 1915, generations of CMU drama students who staged theatrical productions there wrote their names on the brick walls backstage, including Rob "Buz" Marshall, class of '83, who directed the Oscar-winning movie musical "Chicago," and Holly Hunter, star of the television drama "Saving Grace." One student proclaimed themselves a graduate of the "school of trauma."

Today, music students use the Kresge Theater most often while drama students stage most of their productions in the Purnell Center for the Arts, which opened in 1999.

Yet the theater has some issues, Dr. Robinson acknowledged. "We've had to remove all the theatrical rigging from it, which was the original stuff, for health and safety reasons."

During last December's break, the Lawrenceville architectural firm Desmone & Associates supervised a crew that removed "decades of debris" left in the flies of the theater, which hold up the scenery and the curtains.

"I knew there were safety issues in the theater," said Dr. Zahler. "I was concerned that ladders were not enclosed. Catwalks were not particularly stable. [Cleaning crews] found old racks of sound equipment, old lighting fixtures, programs and other remnants of past productions. I just wanted to make sure it was clean and it was safe."

CMU did not record what happened to the decorative pieces removed from Kresge Theater in the 1970s, including a missing stage curtain painted with scenes of Roman monuments, woodwork that covered the footlights or J. Monroe Hewlett's recessed mural panels that depicted Greek dramas and lined the auditorium's walls.

Also missing from the theater is the pipe organ. In his hard hat search, Mr. Garin found the motor to the original pipe organ, but not the pipe organ itself.

Dr. Zahler asked CMU archivists Martin Aurand and Jennie Benford to scour the school's records "to find out what the original specifications were and who was asked to do the work" in Kresge Theater.

"Now that we found the skylight we have a decision to make about how we might restore that or what we're going to do with it," Dr. Robinson said.

Dr. Zahler estimated that improving the theater would cost roughly $3 million.

As for the ceiling, authenticating it as a Tiffany will be challenging, experts say.

Tiffany's New York studios produced decorative windows for many Southwestern Pennsylvania churches during the 19th and 20th centuries. His firm used opalescent glass, an American invention popular between 1880 and 1920 and used by virtually all U.S. glass artisans.

"Tiffany's studios produced numerous skylights for private homes and public buildings," said Nina Gray, a Manhattan-based independent scholar of 19th- and 20th-century decorative arts who is curating a "Tiffany by Design" exhibit in Nashville, Tenn.

The fact that vines and flowers appear to have been used on CMU's ceiling, Ms. Gray said, "is a good sign. It sounds as if it has distinctive ornament that is often seen in Tiffany work."

But authenticating the work will be difficult because Mr. Tiffany's studio was sold in a series of bankruptcies and many records were destroyed, said Arlie Sulka, owner of Lillian Nassau LLC, a New York gallery specializing in Mr. Tiffany's works.

Ms. Benford, the CMU archivist, theorizes that the story of Mr. Tiffany making the Kresge Theater ceiling arose because his studio designed CMU's original logo, which features thistles, the date 1900 and founder Andrew Carnegie's famous words, "My heart is in the work."

CMU's records confirm that Mr. Tiffany's studio designed the logo, which appears in a round piece of stained glass recessed into a ceiling on the third floor of Baker Hall, the administration building. So far, the school has been unable to document who made the Baker Hall stained glass.

Al Tannler, historical collections director at Pittsburgh History & Landmarks Foundation, has studied architectural glass in Pittsburgh since 1994 and has not come across any documented Tiffany skylight or ceiling. People often see opalescent glass and instantly assume it's Tiffany, he said.

One of Pittsburgh's widely seen skylights is in Downtown's Union Trust Building and was made by Rudy Brothers, a local studio of glass artisans. The studio's artistic director, J. Horace Rudy, was taught by Frederick Wilson, Tiffany's chief architectural glass designer from 1894 to 1923, Mr. Tannler said.

Charles L. Rosenblum, who teaches a course at CMU on architect Henry Hornbostel, does not think the leaded-glass ceiling was Mr. Tiffany's work. Mr. Hornbostel won the commission to design the CMU campus and served as the first dean of the College of Fine Arts.

Mr. Rosenblum, who is writing a doctoral dissertation on Mr. Hornbostel, has reviewed College of Fine Arts course catalogs that boasted about the theater's J. Monroe Hewlett murals and Achille Martini's early work on the building's outdoor niches that showcase different facets of the arts and were finally completed in the 1990s.

"There's no mention of Tiffany in these course catalogs," Mr. Rosenblum said.

In addition, he said, Lloyd Hornbostel Jr., the architect's son, "destroyed his father's papers when Henry died."

Unless a researcher discovers some old record by chance, he said, "I don't think we're ever going to know who was the fabricator" of the skylit ceiling.

Dr. Zahler holds out hope that these preservation mysteries of Pittsburgh will be solved.

"Even if it's not Tiffany, we'd like to know whose work it is. It would tell us more about the building."

He asks that anyone who knows the whereabouts of the curtain, mural panels or pipe organ to call 412-268-2384.