Designed collaboratively by Harrison & Abramovitz and A.C. Martin & Associates, construction of the building began in 1965 and was completed in 1968 for the Connecticut General Life Insurance Company.

It was the first skyscraper built in the central business district of Los Angeles as part of the Bunker Hill redevelopment project following the repeal of limitations on construction greater than 150 feet in height in 1957.

Noted landscape architect Garrett Eckbo designed the three-acre modernist outdoor plaza on top of the parking garage.

[5] The property was named for the formerly Los Angeles based Union Bank & Trust Company, who leased 14 floors for their corporate headquarters.

Union Bank Plaza was also acquired by Waterbridge Capital for roughly $110,000,000 in March 2023.