This glass box in the center of Portland, Oregon, has hosted performances by The Beatles, Luciano Pavarotti, and Elvis Presley. The Dalai Lama has spoken within its cavernous volume, as did Barack Obama during his presidential campaign. The Trail Blazers, Portland’s beloved NBA franchise, won its sole championship in the building in 1977, and UCLA took home one of its many titles from the venue a decade before that. Allen Ginsberg, while attending the aforementioned Beatles concert, was struck by inspiration and wrote a poem entitled “Portland Coliseum.”

While its cultural history is impressive, that will not be enough to save the venue from demolition: The Memorial Coliseum has been threatened by a proposal to build a minor league baseball stadium in its place. But the structure’s exquisite beauty and refined engineering has motivated a host of architects, sports fans, historians, artists, and design enthusiasts to join together in an attempt to preserve it.

Designed by Skidmore, Owings & Merrill and dedicated on January 8, 1961, the Memorial Coliseum was shaped in part by Gordon Bunshaft, the firm’s best-known architect, famous for landmarks such as Lever House in New York. It is one of the more unique arenas in the United States, if not the world, because of its high level of transparency. The 12,000-seat seating bowl is structurally independent from the surrounding glass box, which, in spite of its massive four-block expanse, stands on only four columns. When the bowl’s encompassing curtains are drawn open (something that hasn’t happened in many years), the arena can be flooded with natural light.

In the book Modernism Rediscovered, a photograph by legendary architectural photographer Julius Shulman (taken shortly after Memorial Coliseum’s opening) shows the hockey arena during the day without artificial light. This transparency also extends to the outer concourses. Instead of walking through a rabbit warren of interior circulation spaces closed off from the outside, visitors to Memorial Coliseum enter and exit the seating bowl with panoramic floor-to-ceiling views of the downtown skyline.

The coliseum sits in the Rose Quarter, a loosely knit sports-and-event complex that also includes the larger 20,000-seat Rose Garden arena. Most cities upgrading to new professional sports venues have torn down the arenas they replace. Most recently, Philadelphia tore down The Spectrum, which had a history at least as illustrious as Memorial Coliseum’s—but was arguably less architecturally significant. The Rose Garden, however, isn’t the biggest threat to Memorial Coliseum.

The demolition danger has arisen from proposed changes to PGE Park, another stadium across town. Merritt Paulson, owner of the Portland Beavers AAA baseball franchise and the Portland Timbers minor-league soccer team, has won initial approval from Major League Soccer to bring the sport to the Rose City. But MLS prefers its teams to play in soccer-only venues. That means Paulson’s baseball Beavers need to vacate PGE Park so it can be converted for soccer, necessitating the need for a new home for the baseball team.

Initially, Paulson and Portland Mayor Sam Adams hatched a plan for a baseball stadium to replace Memorial Coliseum. But at a public open house in April to introduce the plan, Adams heard a chorus of opposition. Public and media skepticism for the plan has been overwhelming: Two opinion polls found a more than 8-to-1 advantage for those opposing razing the coliseum. The City Council was set to vote on a plan on April 22, but the mayor postponed the vote indefinitely after it became clear that he would lose 3-2. As of this writing, city planners and Paulson’s advisors are considering several alternate locations for a baseball stadium, though the Coliseum site remains an option.

Even if Memorial Coliseum avoids demolition, it could be significantly altered by future Rose Quarter plans. Although owned by the city, billionaire Blazers owner Paul Allen’s Oregon Arena Corporation (OAC) manages the site. The company has proposed opening an entertainment zone inside the coliseum, pending the removal of its distinctive seating bowl. An open-air music venue has also been proposed, which may reduce the arena to a mere skeleton. Research by William Macht, associate director of Portland State University’s Center for Real Estate, also shows that OAC’s management deal gives the company a financial incentive to break even in operating the coliseum, but a disincentive to turn a profit, contributing to the building’s current disrepair.

While the threat to the Coliseum highlights the difficulties faced by mid-20th-century modernist architecture when seeking acceptance as historically significant, there may also be optimism found in its boisterous defense. In this case, a small but vocal group of architects and activists may have successfully stared down the opposing interests of two billionaire sports franchise owners and a sex-scandal-plagued mayor desperate to complete a major project before a recall campaign this summer. So for the time being, when it rains in Portland, which is often, locals can seek solace in their glass palace.