AKA: Century 21 Exposition, Washington State Coliseum, Seattle, WA; KeyArena, Seattle Center, Seattle, WA

Structure Type: built works - exhibition buildings - exposition buildings; built works - performing arts structures - performing arts structures; built works - recreation areas and structures - arenas

Designers: Andersen, Bjornstad and Kane, Incorporated, Consulting Engineers (firm); Hostmark, Peter H., and Associates, Engineers (firm); Mortenson, M.A., Construction Company (firm); Naramore, Bain, Brady, and Johanson, (NBBJ) (firm); PCL Construction Services, Incorporated, Building Contractor (firm); Skanska USA Building Incorporated (firm); Skilling Ward Magnusson Barkshire, (SWMB), Incorporated, Engineers (firm); Thiry, Paul, FAIA, Architect (firm); Wright, Howard S., (HSW) Construction Company (firm); Arthur Andersen (engineer); William James Bain Jr. (architect); William James Bain Sr. (architect); Arthur J. Barkshire (structural engineer); Trygve Bjornstad (engineer); Clifton J. Brady (architect); Howard Burton (structural engineer); Peter H. Hostmark ; Perry Bertil Johanson (architect); Thomas Kane (engineer); Jon Magnusson (structural engineer); Floyd Archibald Naramore (architect); Paul Albert Thiry Sr. (architect); William D. Ward (structural engineer); Howard S. Wright (building contractor/developer)

Dates: constructed 1960-1962

total floor area: 130,000 sq. ft.

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400 1st Avenue North
Seattle Center, Seattle, WA 98109

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Building History

Architect Paul Thiry designed this 130,000-square-foot pavilion to have a large clear span suitable for exhibits. The Official Guide Book to the Seattle World's Fair (p. 26-27) noted of the building's form: "In the shape of a hyperbolic paraboloid, it has no interior roof supports. Four massive concrete abutments support the building's roof, which is 110 feet or 11 stories high. The aluminum paneled roof is supported by steel compression trusses and nearly 6 miles of steel tension cables." It cost $4.5 million to build, and was paid for by the State of Washington, Department of Commerce and Economic Development.

Thiry worked with the structural engineer Peter H. Hostmark (d. 06/18/1969) on the design of the Washington State Coliseum. They collaborated with the Howard S. Wright Construction Company, also the general contractor of the Space Needle at the Seattle World's Fair. The engineering consultants Andersen Bjornstad and Kane assisted Howard S. Wright with the construction process. According to architectural writer Marga Rose Hancock, "Thomas Kane, with Andersen Bjornstad Kane, served as a special advisor to contractor Howard S. Wright during the construction of the Coliseum, assisting with tensioning, ring beams, and cables." (See Marga Rose Hancock, HistoryLink.org, "Century 21 World's Fair — Structural Engineering," published 03/31/2013, accessed 08/14/2019.)

Builders of the Washington State Coliseum envisioned it to be reused as a multi-purpose sports and entertainment arena following the fair. After two years of work transitioning it from exhibit hall to sports arena, it reopened in 1964 as the "Seattle Center Coliseum."

The building was known as the "KeyArena at Seattle Center" between 1995 and 2018. KeyBank of Cleveland, OH, paid $15.1 millionfor naming rights to the Coliseum Arena on 04/11/1995. The bank extended this sponsorship in 03/2009 until 12/2010, at an annual price of $300,000. The name continued to be used for the venue until 2018.

Building Notes

The Washington State Coliseum occupied nearly 4 acres of land in what was the Warren Neighborhood of Lower Queen Anne. Thiry created a design composed of a 400-foot square, within which was a clear span of of several hundred feet. This was accomplished utilizing reinforced concrete edge beams that were post-tensioned. The aluminum roof panels were supported by galvanized wire cables held in tension. The Howard S. Wright Construction Company built the Coliseum.

It served as home for a number of major sports teams including two university basketball programs, the Seattle University Redhawks Basketball Team (1963-1980, 2008-2018 and after 2021-), washington Huskies Basketball Team (1999-2000), two professional basketball franchises, the Seattle SuperSonics of the National Basketball Association, (1967-1978, 1985-1994, 1995-2008) and the Seattle Storm of Women's National Basketball Association (2000-2018, 2021-), and two professional hockey teams, the Seattle Totems Western Hockey League/Central Professional Hockey League (1962–1975), Seattle Thunderbirds (1989–1994, 1995–2008), and a professional soccer team, the Seattle SeaDogs of the Continental Indoor Soccer League (1996-1997).

Tel: 206.684.7200 (2006).


After the 1962 World's Fair, the plan was to convert the Washington State Coliseum to an 18.500-seat sports arena and convention center. It functioned in this way largely unchanged until the early 1990s. The Coliseum underwent a $74 million alteration and enlargement in 1994-1995 to serve as the home of the Seattle Supersonics Basketball Team. NBBJ Architects supervised this renovation and enlargement. Cleveland, OH-based Key Bank entered into a naming rights agreement with the City of Seattle in 1995, resulting in the facility rechristening as the "Key Arena."

By 2006, the Supersonics' ownership claimed that the Key Arena generated insufficient revenue to maintain the team, and other venues were studied to which to move the team. In 2008, the team was moved by its ownership group led by Clay Bennett to Oklahoma City, OK.

Seattle Historic Landmark (Listed 2017-08-02): ID n/a

National Register of Historic Places (Listed 2018-05-10): 100002406 NRHP Images (pdf) NHRP Registration Form (pdf)

PCAD id: 5972

"Presents new opportunities", Architectural Record, 129: 4, 255, 04/1961. "The Fair Becomes Seattle Center", Architectural Record, 133: 2, 32-2 - 32-3, 02/1963. Enlow, Clair, "It's Time to Worry about the Future of KeyArena", Daily Journal of Commerce, 2012-10-24. "Washington State Coliseum", Official Guide Book Seattle World 's Fair 1962, 26-27, 1962. Andriesen, David, "Will the puck stop here? A new arena would be more viable with an NHL team--if Seattle can get one", Seattle Post-Intelligencer, D1, D2, 02/01/2007. Johns, Greg, "City still believes KeyArena can work", Seattle Post-Intelligencer, D2, 06/09/2007. Young, Bob, Brunner, Jim, "Why Sonics are leaving Seattle in 10 easy steps", Seattle Times, A1, A12, 11/14/2006. "What's the rush with Key Arena plan?", Seattle Times, A13, 2017-02-14. Evans, Jayda, "Seattle, Storm agree to lease", Seattle Times, C2, 01/13/2009. Brunner, Jim, "Sonics argue team's economic impact nil", Seattle Times, B1, B4, 06/20/2008. "With the Sonics go TVs, office chairs and radios", Seattle Times, B6, 08/21/2008. Baker, Geoff, "In the Key Arena Debate, the Architects Have the Answers", Seattle Times, C2, 2017-04-17. Allen, Percy, "KeyArena keeps sponsor for 2 years", Seattle Times, B4, 10/07/2008. Baker, Geoff, "NHL Seattle arena still set for 2021 completion", Seattle Times, C1, C3, 2019-09-17. Brodeur, Nicole, "No points for Sonics tax assist", Seattle Times, B1, 10/28/2009. Brunner, Jim, "Key Arena bill 'really dead'", Seattle Times, B1-B2, 04/23/2009. Stone, Larry, "It's Time for Hansen, SODO Supporters to Face Reality", Seattle Times, C1, C4, 2017-06-02. Brunner, Jim, Thomas, Ralph, "Investors float plans, work on legislators to keep NBA", Seattle Times, B1, B4, 2008-03-01. Calkins, Matt, "There Are Reasons to Doubt Key Arena Ideas Can Work", Seattle Times, C1, C4, 2017-01-26. "Vote "no" on city sports initiative", Seattle Times, B6, 2006-10-18. Hasegawa, Robert, "City's court battle: Millions. Fans owning the Sonics: Priceless.", Seattle Times, B9, 07/02/2008. "Century 21 Revisited: A World Fair Enters the Construction Phase", Western Architect and Engineer, 221: 6, 22-26, 06/1961.