In 1998, voters in Seattle agreed to a $200 million modernization of the Seattle Public Library system named 'Libraries for All'. As part of this initiative Rem Koolhaas/OMA in collaboration with the Seattle firm LMN Architects was commissioned in 1999 to build a new library building in downtown Seattle. Joshua Ramus was the partner in charge. The new library opened on May 2004 and it soon became one of the seminal buildings of the early 2000s.

The building epitomizes Rem Koolhaas's interest in the architectural program: the organization of space according to use and function. The library is arranged across five platforms which are derived from a functional diagram of the surface needs for the different library tasks. Together they dictate the building's distinctive shape. Oma wrtites: "By modifying the superposition of floors in the typical American high-rise, a building emerges that is at the same time sensitive (the slopes will admit unusual quantities of daylight where desirable), contextual (each side can react differently to specific urban conditions) and iconic. Its angular facets form a plausible bracketing of Seattle's new modernity."The core platform is the book spiral which arranges and displays the library's entire book collection in a continuous ribbon running from 000 to 999 to allow for the expansion of certain sections without compromising library space.

The spaces between the platforms function as "trading floors" where librarians can inform and stimulate the patrons. They are designed to create spaces for work, interaction and play. In OMA's library configuration the reference desk is called Mixing Chamber. It is untypically placed in the center of the building and functions as the central node to the library's information and people flow.