Sarah Abedelal had no idea that above the ceiling of her public school was a long-forgotten relic of a famed Chicago architect.

Abedelal is the principal for Joseph Brennemann Elementary School in Chicago’s Uptown neighborhood, whose appearance is as uninspiring as a building could be.

It has a long, rectangular structure, with a wall of glass on the first floor, and on the second: a massive, steel enclosure not unlike a self-storage unit.

Under the steel facade though, are intricately curved concrete shells, coverings for still intact windows long hidden from the outside – and the 24 classrooms below –for three decades.

The school’s architect was Bertrand Goldberg.

You may recognize Goldberg’s famous Marina City, the twin corncob towers on the Chicago River. Some of his other Chicago buildings include River City in the South Loop and Hilliard Homes near Chinatown.

Goldberg, a modernist Chicago architect with a flair for curving concrete forms, designed some of the city’s most distinctive buildings in the ‘60s and ‘70s.

Some, such as Marina City, are beloved city treasures. Others, such as Prentice Women’s Hospital, have met the fate of a wrecking ball.

The late, flower-shaped Streeterville hospital was completed in 1975 and torn down in 2014 by Northwestern University to make way for a larger replacement.

More recently, new owners began whitewashing the interior common spaces of River City, abandoning the textured, concrete look that distinguished Goldberg’s style.

It so happens, that there’s a bit of Goldberg conservation hiding at the school at 4521 N. Clarendon Avenue.

Abdelal, who’s been Brennemann’s principal for twelve years, said the attic was a surprise to her at first, too. Someone, she can’t recall who, told her to check out what was at the top of a ladder in a storage closet, and when she got to the top, “I couldn’t believe all this was up here.”

The curved forms, a collection of 24 parabaloid skylights 30 feet above every classroom, was an intentional break with the classically boxy look of schools.

Brennemann was built between 1961 to 1963, and the shell framed a north-facing wall of glass would shine sunlight down into the classrooms.

Goldberg saw these individual shells as a modern take on the historical one-room schoolhouse. Goldberg wrote that “historically, schools have been built so institutionally that children are either freighted by them or conditioned by them to fit into an institutional society.”

“I firmly believe that there is need for schools which are scaled both in concept and in size to young people who will be using them and who, I hope, will grow as individualists.”

In 1963, you would have seen glassed waves rolling across the school. Now, it’s replaced with an unsightly metal box that was erected in 1984 because the roof leaked not long after it opened.

As originally designed, Abdelal said, the classrooms would have a lot of daylight. Now, they have few or no windows at all.

Graceless as it is, the rooftop box was the solution to a staggering problem. Construction had started in June 1961, and in November, one of the concrete shells collapsed, halting construction and delaying the school’s opening by a full school year.

The school building passed engineering tests before it opened, but from early on, parents complained about the roof leaking.

In 1973, a Chicago Board of Education official told the Chicago Tribune that the roof leaked and plaster was falling from the walls and ceiling.

Another 11 years passed before the Board announced that it would build a steel cap over Goldberg’s shells. Knocking down all that concrete would have been impractical, so instead, the Goldberg structure was left hidden in the attic – where it remains today.

Dennis Rodkin is a real estate reporter for Crain’s Chicago Business and Morning Shift’s “What’s That Building?” contributor.

