It has been a whole six years since visitors of Lincoln Center have been able to see Orpheus and Apollo, a shimmering mid-century modern art installation that previously floated above the lobby of the New York Philharmonic's concert hall for half a century. Removed in 2014 for "maintenance and conservation" and put into storage in New Jersey, the highly intricate gold-colored metallic sculpture by the acclaimed artist Richard Lippold will not be a part of the new $550 million redesign of what is now called David Geffen Hall.

But on the heels of an important historic designation, some preservationists are ramping up an effort to restore the artwork, which they say is an integral element not only of Geffen hall but the entire Lincoln Center complex.

On Wednesday, the Preservation League of New York put the Lippold work on its "Seven To Save" list, a biennial compilation of the most at-risk historic places in the state.

Sean Khorsandi, the executive director of Landmark West, a preservation group on the Upper West Side, was among those who worked behind-the-scenes to get the piece included in the Preservation League's list.

"Richard Lippold's understanding of the relationship between art and architecture was truly innovative; he designed Orpheus and Apollo to activate and enhance the space in Philharmonic Hall," he told Gothamist. The removal of the work, he argued, amounts to the "slow eroding" of Lincoln Center's architectural integrity.

Under the long-awaited redevelopment plan for Geffen Hall, the new lobby will double in size and become a more flexible space that will allow for a media streaming wall that broadcasts performances in real time, a bistro and more bars, as well as a welcome center. As some have pointed out, the design follows on the more-than-a decade-old movement by arts and culture institutions to build bigger open spaces that are conducive to external event rentals, which have become a major stream of revenue.

Amid this new financial calculus, critics of the plan have observed that a five-ton, 190-foot-long, 39-foot-high abstract installation may be seen as getting in the way of programming or special events.

"It’s an unfortunate trend," said Liz Waytkus, the executive director of Docomomo US, an organization that works on preserving modern design. "Interiors are so easily lost. But it’s how we engage with a space."

She added: "When you remove the human-scale elements, you destroy meaning, you destroy connection."

In a statement, Isabel Sinistore, a spokesperson for Lincoln Center, acknowledged the importance of the piece as a "critical" part of the building's history.

"Lincoln Center, the New York Philharmonic, and our design team worked hard to try and find a way for the sculpture to be reinstalled in the renovated David Geffen Hall," she said. "One of our big priorities for this project is fostering a greater sense of community and connection. Key to achieving this is welcoming new audiences for all kinds of experiences, including performances and educational activities in the Grand Promenade outside the main hall. Regrettably, in order to configure the space to meet these goals we will be unable to reinstall the sculpture in David Geffen Hall."

She added that Lincoln Center is in "active discussions" with the Lippold Foundation and others to find a new home for the sculpture.

Over the decades, changes made to the sprawling 1960s Lincoln Center complex—including the $1.2 billion overhaul that targeted the public areas—have been a fraught issue for preservationists who maintain that the buildings and spaces were designed to work in concert with another. To their chagrin, the campus has never been designated an official landmark by the city's Landmarks Preservation Commission. In 2000, the site was made eligible for a listing on the state and national registers of historic places, but Lincoln Center officials declined to be considered.

Had they accepted the designation, state preservation officials would have had more say in renovations, including over the removal of a sculptural centerpiece like the Lippold work, Khorsandi said.

Some experts like Michael Gotkin, a preservationist who has spearheaded other causes, have said that appreciation for Lippold, who died in 2002, has only grown over time. In his obituary, the New York Times described him as "less a pure formalist, however, than a lyric poet of space and light."

Another famous wire sculpture by the artist, Flight, is installed in one of the lobbies of the MetLife building.

Along with Flight, Orpheus and Apollo is considered two of Lippold's most important public works. But its years-long absence has threatened to make the New Yorkers forget about its existence.

"There's a whole generation of young people since 2014 that aren’t even aware that there is a sculpture there," said Theodore Grunewald, who has over the years launched legal battles to save relics of modern art and architecture in New York City.

Now, with the latest designation, he said, "It’s going to finally get some public awareness."