Rainier Square Tower, Modern skyscraper in Downtown Seattle, United States.

Rainier Square Tower is a modern skyscraper in downtown Seattle that rises to about 850 feet with a tapered silhouette. The building integrates office space, luxury residential units, and retail areas throughout its 58 levels.

The University of Washington, owner of the Metropolitan Tract, announced plans in late 2013 to redevelop the Rainier Square shopping center, which had opened in 1978. After Wright Runstad was chosen in May 2014, the tower's height was raised to 850 feet in November 2015 and the master use plan was approved that December. Demolition began in September 2017, steel core erection started in October 2018, and the building was topped out in August 2019 and completed in September 2020.

The tower's slanted design allows views of the neighboring Rainier Tower to remain unobstructed, creating a visual relationship between old and new buildings. This thoughtful positioning shows how contemporary Seattle construction considers what already exists in the cityscape.

The tower stands at Union Street between 4th and 5th Avenues, beside the older Rainier Tower with its pedestal base. Six levels of parking below ground hold up to 1,000 vehicles. The retail spaces at street level face Union Street; a Mendocino Farms restaurant opened on the northwest corner in September 2023.

The building uses an innovative steel plate shear wall system in its core, which differs from typical construction methods used in most skyscrapers. This engineering choice helps provide structural stability while allowing for flexible interior layouts on each floor.