Construction on the building began in 1944, with it opening in 1948 as the Equitable Building. The building, which was built as the headquarters in Portland of the
Equitable Savings and Loan Association, was originally intended to be 12 stories high but was later expanded to 14. It was the first tower to be sheathed in
aluminum, the first to use double-glazed window panels, and was the first to be completely sealed and fully
air-conditioned. The Commonwealth Building was added to the
National Register of Historic Places (as the Equitable Building) in 1976. In 1980, the
American Society of Mechanical Engineers (ASME) designated the Commonwealth Building as a National Historic Mechanical Engineering Landmark. In 1982, the building was the recipient of the
Twenty-five Year Award, of the
American Institute of Architects. In 1993, Weston Investment Co. LLC bought the building for $1.9 million.
Unico Properties and Cigna Realty Investors bought the building in 2007 from Weston for $27 million, and spent $7 million more on renovations to the structure. The building was sold again by Unico in 2013 for $41 million when Unico bought out Cigna. Unico sold the tower to KBS in 2016 for $69 million. Commonwealth Property Owner LLC took possession on a $15,000,000
trust deed in July 2023, who then sold it for $6.5 million in December 2025. ==Features==