The iconic roof structure of KeyArena on the Seattle Center grounds will be the only remaining part of the original coliseum after it is redeveloped into an NHL and NBA venue. Because the ongoing excavation is lowering the ground level beneath the existing footings, a network of temporary steel supports is necessary to hold up the roof structure until new foundations can be placed. Now called the Seattle Center Arena, the coliseum is scheduled to open in the spring of 2021, in time for the new Seattle NHL franchise. Oak View Group is the developer for the project; Populous is the architecture firm; and Mortenson is the general contractor.

Paul Thiry designed the original structure, the Washington State Pavilion for the 1962 World’s Fair—the Century 21 Exposition. It was soon renamed the Seattle Center Coliseum, which served as a venue for sports, concerts, and other entertainment over the decades. In 1994–95, NBBJ-designed a renovation to bring the coliseum up to NBA standards and and naming rights were sold to KeyBank, which renamed the coliseum KeyArena. Notably, the coliseum was the home of the Seattle SuperSonics before the team’s sale in 2006 and ultimate move to Oklahoma City in 2008.

This second drawing of the arena’s roof structure is from a slightly different point of view and strips away much of the surrounding activity to focus primarily on the shell.