The Union Bank Tower, formerly known as the Union Bank of California Tower and originally as the Bank of California building, is an 82 m (269 ft), 15-story office building completed in 1969 in downtown Portland, Oregon. It was briefly the tallest building in the city when it topped-out in 1968, but was soon eclipsed by the Georgia-Pacific Building.

The Bank of California was opened in San Francisco, California, on July 4, 1864, by William Chapman Ralston and Darius Ogden Mills. It was the first commercial bank in the Western United States, and considered instrumental in developing the American Old West.