The coliseum is an approximately 360' x 85' cube sheathed in a dark-tinted glass curtain wall topped by a fascia band. The 22' high, white fascia band conceals the roof trusses from the exterior. Breaking the rigid geometry of the exterior is a free-standing, white entrance canopy with a gently up-curving roof supported by four tapered columns. On the interior is a roughly circular, white seating bowl surrounding an oval main floor. The seating bowl is free-standing within the cube and is entered at mid-level from the surrounding lobby areas and principal building entrances. The main floor is then sunken a level down. Surrounding the main floor on the lower level are seven meeting and banquet rooms. Seating capacity ranges from 9,000 in fixed seating to a maximum of 13,500 including movable bleachers.
Four cruciform concrete columns support a two-way system of steel roof trusses. The grey-tinted glass curtain walls are hung from the tapered ends of the trusses and capped with a the solid fascia band of acrylic overlaid plywood. The entrance canopy is wood framed. On the interior laminated wood columns are used to brace the tall curtain walls against lateral wind loads and the oval seating bowl is concrete. Hiding the trusses is a suspended ceiling over the coliseum floor and surrounding lobby areas.
Memorial Coliseum is located in a 30 acre area known as the Rose Quarter on the west bank of the Willamette River in downtown Portland. The Rose Quarter also incudes the newer Rose Garden Arena, three restaurants, four parking garages, corporate offices and a large pedestrian plaza. Under the entry plaza adjacent to the Coliseum is the 40,000 square foot Exposition Hall.
Technical innovation includes a retracting fabric curtain system between the top of the seating bowl and the roof. When darkening is not required the retracting curtain allows natural light to reach the center of the building and for exterior views from the seats. The combination of light and views is a rarity in indoor sports and multipurpose venues where the seating is normally sealed off from any experience of the outdoors.
The coliseum had the most social impact by making Portland a city capable of hosting sports teams requiring an indoor venue, as well as large-scale conference and entertainment events. The construction of multipurpose venues capable of attracting sports teams has continued to be a priority for city governments across the country that want to enhance the lives of their citizens and gain status.
The most striking aesthetic aspect of the design, best visible when the building is illuminated at night, is the contrast of the rigidly symmetrical exterior form to the curving seating bowl within.
Architects Skidmore, Owings & Merrill (S.O.M.) took over Pietro Belluschi's Portland office in the 1950s and completed a number of locally- and regionally-influential projects including the Memorial Coliseum. While the building fits into the firm's national body of work, it is also unusual in being an an early application of the firm's signature modernist style of the period to a rather unlikely building type.
Memorial Coliseum represents an well-executed application of modern design principles to a sports and multipurpose venue. When constructed the building was innovative both technically and visually, and elevated the status of Portland as a city.