Union Bank of California Tower, High-rise building in downtown Portland, Oregon

Union Bank of California Tower is a 15-story, 82 m office building completed in 1969 at 111 SW 5th Avenue in downtown Portland. Designed by Anshen & Allen of San Francisco in the International Style, it has exposed service cores on its south and west sides clad in light gray slate with a greenish tint. The interior was led by New York designer Maria Bergson.

Built for the Bank of California, whose Portland offices had outgrown the 1925 bank building a block east, the tower rose from 1967 on a full block that had held the 1889 Rosenblatt Building and two theatres. It topped out in 1968 as the city's tallest, was eclipsed by the Georgia-Pacific Building, and the bank moved in on December 8, 1969. Developer Harry Mittleman bought it in 1972 and kept an office on the 15th floor.

The architectural firm Anshen and Allen incorporated International Style elements into the design, reflecting the commercial development of Portland during the late 1960s.

The tower is best viewed from street level, where its distinctive slate cladding and exposed structure are clearly visible. Visitors can explore the building from the outside and observe its architectural details from various vantage points downtown.

The building's exposed service cores on the south and west sides are clad in light gray slate with a greenish tint, said to have been quarried in the same area of Wales as the stone used at Stonehenge. The cores stand outside the main volume, so the slate reads as a separate band against the glass.