As the Pittsburgh Penguins’ final season wound to a close this spring, the debate over the historic Mellon Arena’s fate shifted into high gear. The hockey arena, dubbed the “Igloo” for its iconic domed roof, was the largest dome in the world when it was built in 1961. Though that record was soon displaced, it has remained unchallenged for the honor of having the world’s largest retractable steel dome roof.

Designed by eminent engineers Ammann & Whitney of New York, the dome comprises a steel truss system covered with a metal deck and a lightweight stainless steel skin. Its eight leaves rotate out on railroad tracks to form a closed, self-supporting dome, and rotate in to open the dome three-quarters of the way to the sky. When fully retracted, the roof is entirely supported by a 260-foot cantilevered arm—essentially half of an arch bridge—anchored at its base in large caissons.

The Igloo’s owners, the Sports & Exhibition Authority (SEA), gave the Pittsburgh Penguins the development rights to the Igloo and its surrounding 28-acre property, and the Penguins have publicized their plans to raze the arena and replace it with offices, retail, hotels, and entertainment. As the team and the SEA urge speed, citing the costs of maintaining the closed arena, activists have been pleading for time to make the case for preservation.

Among the leaders of the preservation movement is the nonprofit Reuse the Igloo, founded by architect Rob Pfaffmann, who led an unsuccessful campaign in 2003 to have the arena designated a city historic structure. His own proposal for saving the arena includes mixed-use development around the Igloo but would transform the arena itself into a public space. Pfaffmann envisions leaving the dome open for most of the year and removing the interior seating bowl to clear floorspace that could be used for festivals or ice skating. Citing Bryant Park and the High Line in New York, he argues that an innovative reuse of the arena would do far more to attract visitors and boost real estate than a new mixed-use development would.

The battle over the Igloo is being waged both politically and economically. From a financial perspective, a report recently prepared by the SEA’s consultant, Oxford Development, estimates a $103.5 million windfall from the Penguins’ plan to raze the arena and replace it with mixed-use development. They project only a $53.8 million benefit from Reuse the Igloo’s plan.

However, Todd Poole, president of 4ward Planning, the consultant hired by Reuse the Igloo, argues that the Oxford estimate engages in double-counting. The new tenants they expect will more likely come from businesses relocating from other parts of the city, and the money they foresee being spent on new retail would otherwise have been spent on old retail, he said. “Ultimately, they’re going to be diverting dollars from merchants who have been there for many years and who are only just starting to rebound,” Poole explained.

The debate over the Igloo’s future is also complicated politically by its checkered past. Its construction was part of one of the city’s major urban renewal schemes that severed the street grid, isolating the predominantly African American Hill District from the city’s downtown on the other side of the arena. “Hill District residents are split,” Pfaffmann said. “Some think it should be symbolically erased from the face of the earth.” While city leaders like Mayor Luke Ravenstahl advocate for the benefits of reconnecting the street grid by removing the arena, Pfaffmann and other preservationists argue that with adaptive reuse, the arena can transcend its past as a barrier and begin to function instead as a connector.